Instll phx_new 1.5.1 and possible ssl issue

Hi sorry for probably silly question but I’m very new here mix archive.install hex phx_new 1.5.1
return ssl issue I think there is some way to add this certificatie? or how to solve it?

mix archive.install hex phx_new 1.5.1

11:48:08.950 [info] TLS :client: In state :certify at ssl_handshake.erl:1781 generated CLIENT ALERT: Fatal - Unknown CA

11:48:08.950 [info] TLS :client: In state :certify at ssl_handshake.erl:1781 generated CLIENT ALERT: Fatal - Unknown CA

Failed to check for new Hex version

Failed to fetch record for 'hexpm/phx_new' from registry (using cache instead)

{:failed_connect, [{:to_address, {'repo.hex.pm', 443}}, {:inet, [:inet], {:tls_alert, {:unknown_ca, 'TLS client: In state certify at ssl_handshake.erl:1781 generated CLIENT ALERT: Fatal - Unknown CA\n'}}}]}

{:failed_connect, [{:to_address, {'repo.hex.pm', 443}}, {:inet, [:inet], {:tls_alert, {:unknown_ca, 'TLS client: In state certify at ssl_handshake.erl:1781 generated CLIENT ALERT: Fatal - Unknown CA\n'}}}]}

** (Mix) No package with name phx_new (from: mix.exs) in registry

1. mix hex --version
  Hex v0.20.5
2. osx
  Catalina 10.15.4
3. mix
mix --version
Erlang/OTP 22 [erts-10.7.1] [source] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:1] [hipe] [dtrace]
Mix 1.10.3 (compiled with Erlang/OTP 22)