Separate dialyzer job

Author: michalmuskala

.github/workflows/ci.yml

@@ -9,7 +9,7 @@ on:
 jobs:
   mix_test:
     name: mix test (Elixir ${{matrix.elixir}} | OTP ${{matrix.otp}})
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-latest
     strategy:
       fail-fast: false
       matrix:
@@ -37,7 +37,6 @@ jobs:
           - elixir: 1.13.x
             otp: 24
             warnings_as_errors: true
-            static_analysis: true
     env:
       MIX_ENV: test
     steps:
@@ -62,5 +61,28 @@ jobs:
       - run: mix compile --warnings-as-errors
         if: matrix.warnings_as_errors
       - run: mix test
+  dialyzer:
+    name: mix dialyzer
+    runs-on: ubuntu-latest
+    env:
+      MIX_ENV: test
+    steps:
+      - uses: actions/checkout@v2
+      - uses: erlef/setup-beam@v1
+        with:
+          otp-version: 24
+          elixir-version: 1.13.x
+      - name: Install Dependencies
+        run: |
+          mix local.hex --force
+          mix local.rebar --force
+          mix deps.get --only test
+      - name: Cache build artifacts
+        uses: actions/cache@v2
+        with:
+          path: |
+            ~/.hex
+            ~/.mix
+            _build
+          key: dialyzer
       - run: mix dialyzer --halt-exit-status
-        if: matrix.static_analysis