feat: upgrade runtime and system dependencies (#5)

* Upgrade elixir, erlang, and postgres to their latest versions.
* Fix CI configuration, so tests are executed.
* Migrate project configuration from `Mix.Config` to `Config`.

Reviewed-on: #5

config/config.exs

@@ -5,7 +5,7 @@
 # is restricted to this project.
 
 # General application configuration
-use Mix.Config
+import Config
 
 config :wabanex,
   ecto_repos: [Wabanex.Repo]
@@ -32,4 +32,4 @@ config :phoenix, :json_library, Jason
 
 # Import environment specific config. This must remain at the bottom
 # of this file so it overrides the configuration defined above.
-import_config "#{Mix.env()}.exs"
+import_config "#{config_env()}.exs"

config/dev.exs

@@ -1,11 +1,8 @@
-use Mix.Config
+import Config
 
 # Configure your database
 config :wabanex, Wabanex.Repo,
-  username: System.get_env("POSTGRES_USER") || "postgres",
-  password: System.get_env("POSTGRES_PASS") || "postgres",
   database: "wabanex_dev",
-  hostname: System.get_env("POSTGRES_HOST") || "localhost",
   show_sensitive_data_on_connection_error: true,
   pool_size: 10
 

config/prod.exs

@@ -1,4 +1,4 @@
-use Mix.Config
+import Config
 
 # For production, don't forget to configure the url host
 # to something meaningful, Phoenix uses this information

config/runtime.exs

@@ -0,0 +1,6 @@
+import Config
+
+config :wabanex, Wabanex.Repo,
+  username: System.get_env("POSTGRES_USER") || "postgres",
+  password: System.get_env("POSTGRES_PASS") || "postgres",
+  hostname: System.get_env("POSTGRES_HOST") || "localhost"

config/test.exs

@@ -1,4 +1,4 @@
-use Mix.Config
+import Config
 
 # Configure your database
 #
@@ -6,10 +6,7 @@ use Mix.Config
 # to provide built-in test partitioning in CI environment.
 # Run `mix help test` for more information.
 config :wabanex, Wabanex.Repo,
-  username: System.get_env("POSTGRES_USER") || "postgres",
-  password: System.get_env("POSTGRES_PASS") || "postgres",
   database: "wabanex_test#{System.get_env("MIX_TEST_PARTITION")}",
-  hostname: System.get_env("POSTGRES_HOST") || "localhost",
   pool: Ecto.Adapters.SQL.Sandbox
 
 # We don't run a server during test. If one is required,