An error occurred while pushing code to Gigalixir

I am trying to push code to Gigalixir. But I got an error. Could you give me some advice by looking log?

thanks.

log

C:\elixir_dev\gigalixir_nodb>git push gigalixir master
Enumerating objects: 558, done.
Counting objects: 100% (558/558), done.
Delta compression using up to 4 threads
Compressing objects: 100% (516/516), done.
Writing objects: 100% (558/558), 5.21 MiB | 1.08 MiB/s, done.
Total 558 (delta 60), reused 0 (delta 0)
remote: Setting environment variables.
remote: * LIBCLUSTER_KUBERNETES_SELECTOR
remote: * LIBCLUSTER_KUBERNETES_NODE_BASENAME
remote: * APP_NAME
remote: * SECRET_KEY_BASE
remote: * PORT
remote: * SOURCE_VERSION
remote: Cloning into 'curvy-secondhand-reindeer'...
remote: warning: You appear to have cloned an empty repository.
remote: done.
remote: Compiling code and generating slug.
remote: latest: Pulling from gigalixir-152404/herokuish
remote: Digest: sha256:01b2c78943f694bcb5e18d7305aa444fe8205007bd93c5b6ae4648a0c63a809a
remote: Status: Image is up to date for us.gcr.io/gigalixir-152404/herokuish:latest
remote: us.gcr.io/gigalixir-152404/herokuish:latest
remote:        ----->        Detecting assets directory
remote:        package.json found in assets directory
remote:        Elixir+Phoenix app detected
remote:        Detecting assets directory
remote:        package.json found in assets directory
remote: =====> Downloading Buildpack: https://github.com/gigalixir/gigalixir-buildpack-clean-cache.git
remote: =====> Detected Framework: Clean Cache
remote:        Not cleaning cache
remote: =====> Downloading Buildpack: https://github.com/HashNuke/heroku-buildpack-elixir.git
remote: =====> Detected Framework: Elixir
remote: -----> Will export the following config vars:
remote:        APP_NAME
remote:        LIBCLUSTER_KUBERNETES_NODE_BASENAME
remote:        LIBCLUSTER_KUBERNETES_SELECTOR
remote:        PORT
remote:        SECRET_KEY_BASE
remote:        SOURCE_VERSION
remote:        * MIX_ENV=prod
remote: -----> Checking Erlang and Elixir versions
remote:        WARNING: elixir_buildpack.config wasn't found in the app
remote:        Using default config from Elixir buildpack
remote:        Will use the following versions:
remote:        * Stack cedar-14
remote:        * Erlang 20.1
remote:        * Elixir 1.5.3
remote: -----> Using cached Erlang 20.1
remote: -----> Installing Erlang 20.1
remote:
remote: -----> Using cached Elixir v1.5.3
remote: -----> Installing Elixir v1.5.3
remote: -----> Installing Hex
remote:        * creating /app/.mix/archives/hex-0.20.1
remote: -----> Installing rebar
remote:        * creating /app/.mix/rebar
remote:        * creating /app/.mix/rebar3
remote: -----> Fetching app dependencies with mix
remote:        Resolving Hex dependencies...
remote:        Dependency resolution completed:
remote:        Unchanged:
remote:        cowboy 2.7.0
remote:        cowlib 2.8.0
remote:        gettext 0.17.4
remote:        jason 1.1.2
remote:        mime 1.3.1
remote:        phoenix 1.4.12
remote:        phoenix_html 2.13.3
remote:        phoenix_pubsub 1.1.2
remote:        plug 1.8.3
remote:        plug_cowboy 2.1.1
remote:        plug_crypto 1.0.0
remote:        ranch 1.7.1
remote:        telemetry 0.4.1
remote:        * Getting phoenix (Hex package)
remote:        * Getting phoenix_pubsub (Hex package)
remote:        * Getting phoenix_html (Hex package)
remote:        * Getting gettext (Hex package)
remote:        * Getting jason (Hex package)
remote:        * Getting plug_cowboy (Hex package)
remote:        * Getting cowboy (Hex package)
remote:        * Getting plug (Hex package)
remote:        * Getting mime (Hex package)
remote:        * Getting plug_crypto (Hex package)
remote:        * Getting cowlib (Hex package)
remote:        * Getting ranch (Hex package)
remote:        * Getting telemetry (Hex package)
remote: -----> Copying hex from /app/.mix/archives/hex-0.20.1
remote: -----> Compiling
remote: ==> gettext
remote: warning: the dependency :gettext requires Elixir "~> 1.6" but you are running on v1.5.3
remote:        Compiling 1 file (.yrl)
remote:        Compiling 1 file (.erl)
remote:        Compiling 20 files (.ex)
remote:
remote: == Compilation error in file lib/mix/tasks/compile.gettext.ex ==
remote:        ** (CompileError) lib/mix/tasks/compile.gettext.ex:2: module Mix.Task.Compiler is not loaded and could not be found
remote:        (elixir) expanding macro: Kernel.use/1
remote:        lib/mix/tasks/compile.gettext.ex:2: Mix.Tasks.Compile.Gettext (module)
remote: could not compile dependency :gettext, "mix compile" failed. You can recompile this dependency with "mix deps.compile gettext", update it with "mix deps.update gettext" or clean it with "mix deps.clean gettext"
remote: Command '[u'docker', u'run', u'--memory-reservation=512m', u'--rm', u'-e', u'GIGALIXIR_SHOULD_CLEAN_CACHE=False', u'-v', u'/tmp/tmpV0dez0/curvy-secondhand-reindeer:/tmp/app', u'-v', u'/tmp/gigalixir/cache/curvy-secondhand-reindeer/:/tmp/cache', u'-v', u'/tmp/tmpV0dez0/env:/tmp/env', u'--env=USER=www-data', u'us.gcr.io/gigalixir-152404/herokuish:latest']' returned non-zero exit status 1
To https://git.gigalixir.com/curvy-secondhand-reindeer.git
 ! [remote rejected] master -> master (pre-receive hook declined)