ci: add lint makefile job

Currently, there is no CI job to lint the Makefile. This adds one.

.gitea/workflows/ci.yml

@@ -23,6 +23,22 @@ jobs:
         with:
           version: latest
 
+  lint-makefile:
+    name: Lint Makefile
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+
+      - name: Install gremlins
+        run: go install github.com/checkmake/checkmake/cmd/checkmake@latest
+
+      - name: Run mutation tests
+        run: make lint-makefile
+
   test-unit:
     name: Unit Tests
     runs-on: ubuntu-latest