Add a basic CI workflow

.github/workflows/ci.yml

@@ -0,0 +1,47 @@
+name: CI
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+    branches: [master]
+
+jobs:
+  test:
+    name: Elixir ${{ matrix.elixir }} / OTP ${{ matrix.otp }}
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        include:
+          - elixir: "1.15"
+            otp: "26"
+          - elixir: "1.17"
+            otp: "27"
+          - elixir: "1.18"
+            otp: "27"
+          - elixir: "1.19"
+            otp: "28"
+
+    steps:
+      - uses: actions/checkout@v6.0.2
+
+      - uses: erlef/setup-beam@v1.20.4
+        with:
+          elixir-version: ${{ matrix.elixir }}
+          otp-version: ${{ matrix.otp }}
+
+      - name: Install dependencies
+        run: mix deps.get
+
+      - name: Compile
+        run: mix compile --warnings-as-errors
+
+      - name: Check Formatting
+        run: mix format --check-formatted
+
+      - name: Run tests
+        run: mix test
+
+      - name: Check docs
+        run: mix docs --warnings-as-errors