Add basic CI setup (#30)

Co-authored-by: Rafael Epplée <hello@rafa.ee>
Reviewed-on: #30
Co-authored-by: Moritz <moritz.m@local-it.org>
Co-committed-by: Moritz <moritz.m@local-it.org>

Justfile

@@ -5,4 +5,22 @@ install-dependencies:
     mix deps.get
 
 migrate-database:
-    mix ecto.create
+    mix ecto.create
+
+reset-database:
+    mix ecto.reset
+
+ci-dev: lint audit test
+
+lint:
+    mix format --check-formatted
+    mix compile --warnings-as-errors
+    mix credo
+
+audit:
+    mix sobelow --config
+    mix deps.audit
+    mix hex.audit
+
+test:
+    mix test