CI: Add os to the matrix of docker-ci.yml

Publish jobs won't have those as it's pointless for them to build and throw away the result, that's what CI is for

.github/workflows/docker-ci.yml

@@ -11,8 +11,9 @@ jobs:
       fail-fast: false
       matrix:
         file: [Dockerfile, Dockerfile.Service]
+        os: [macos-latest, ubuntu-latest, windows-latest]
 
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
 
     steps:
     - name: Checkout code
@@ -23,7 +24,7 @@ jobs:
     - name: Set up Docker Buildx
       uses: docker/setup-buildx-action@v1
 
-    - name: Build Docker image from ${{ matrix.file }}
+    - name: Build Docker image on ${{ matrix.os }} from ${{ matrix.file }}
       uses: docker/build-push-action@v2
       with:
         context: .