add gitea action for unit tests

.gitea/workflows/test.yaml

@@ -0,0 +1,14 @@
+name: Elixir tests
+run-name: Running AoC Unit tests
+on: [push]
+
+jobs:
+  Explore-Gitea-Actions:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out repository code
+        uses: actions/checkout@v4
+      - uses: erlef/setup-beam@v1
+        with:
+          version-file: .tool-versions
+      - run: mix test