Adapter Ecto.Adapters.Mariaex was not compiled

I am new to Elixir, so to learn I’m converting an existing NodeJS project into an Elixir one.

I intend to use plain Elixir (no frameworks), Poison (for JSON I/O), MySQL (database).

My mix dependencies:

[
  {:ecto_sql, "~> 3.2"},
  {:poison, "~> 5.0"},
  {:myxql, "~> 0.6.0"}
]

I followed instructions regarding PostgreSQL on StackOverflow and entered command mix deps.clean --all and then mix do deps.get, compile which results in:

** (ArgumentError) adapter Ecto.Adapters.Mariaex was not compiled, ensure it is correct and it is included as a project dependency
    (ecto 3.11.1) lib/ecto/repo/supervisor.ex:61: Ecto.Repo.Supervisor.compile_config/2
    lib/mysql.ex:2: (module)

I tried adding Mariaex to the dependencies:

[
  {:ecto_sql, "~> 3.2"},
  {:poison, "~> 5.0"},
  {:myxql, "~> 0.6.0"},
  {:mariaex, ">= 0.0.0"}
]

and the result was:

Because "mariaex >= 0.9.0-rc.0" depends on "decimal ~> 1.2" and "mariaex < 0.9.0-rc.0" depends on "decimal ~> 1.0", "mariaex" requires "decimal ~> 1.0".
And because "poison >= 5.0.0" depends on "decimal ~> 2.0", "poison >= 5.0.0" is incompatible with "mariaex".
And because "your app" depends on "mariaex >= 0.0.0", "poison >= 5.0.0" is forbidden.
So, because "your app" depends on "poison ~> 5.0", version solving failed.
** (Mix) Hex dependency resolution failed

I tried removing versions in dependencies:

[
  {:ecto_sql, ">= 0.0.0"},
  {:poison, ">= 0.0.0"},
  {:myxql, ">= 0.0.0"},
  {:mariaex, ">= 0.0.0"}
]

and got:

Because "mariaex >= 0.9.0-rc.0" depends on "decimal ~> 1.2" and "mariaex < 0.9.0-rc.0" depends on "decimal ~> 1.0", "mariaex" requires "decimal ~> 1.0".
And because "the lock" specifies "decimal 2.1.1", "the lock" is incompatible with "mariaex".
And because "your app" depends on "the lock", no version of "mariaex" is allowed.
So, because "your app" depends on "mariaex >= 0.0.0", version solving failed.
** (Mix) Hex dependency resolution failed

Is a connection between Ecto and MySQL even possible? What am I missing?