ci: Simplify Docker image build workflow

Github is deprecating ubuntu-20.04 image and since testing was depending on that specific version I have to remove imate test part for now

.github/workflows/docker-build.yml

@@ -20,48 +20,10 @@ jobs:
   golangci:
     uses: ./.github/workflows/golangci-lint.yml
 
-  test-docker-image:
-    needs: [golangci]
-    # Ubuntu-20.04 required until this is fixed: https://github.com/actions/runner-images/discussions/9074
-    runs-on: ubuntu-20.04
-    steps:
-      - name: Checkout GitHub Action
-        uses: actions/checkout@v4
-
-      - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3
-
-      - name: Build amd64 image for testing
-        uses: docker/build-push-action@v6
-        with:
-          context: .
-          tags: birdnet-go:test
-          load: true
-          platforms: linux/amd64
-          cache-from: type=gha
-          cache-to: type=gha,mode=max
-
-      - name: Install alsa dummy module for testing built image
-        run: |
-          sudo apt-get install linux-modules-extra-$(uname -r)
-          sudo modprobe snd-dummy
-
-      - name: Test built amd64 image
-        run: |
-          docker run --rm -p 8080:8080 --device /dev/snd --env ALSA_CARD=0 birdnet-go:test realtime --source "Dummy" & p1=$!
-          if ! wget --retry-connrefused --waitretry=1 --tries=5 -q -O /dev/null http://localhost:8080; then
-            echo "Failed to reach container after 5 sec"
-            kill "$p1"
-            exit 1
-          else
-            echo "Container responded to request"
-            kill "$p1"
-          fi
-
-  push-docker-image:
-    needs: test-docker-image
+  build-and-push-docker-image:
+    needs: golangci
     if: github.event_name == 'push' && github.ref_name == 'main'
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     steps:
       - name: Checkout GitHub Action
         uses: actions/checkout@v4