chore: do not spend time on building the Docker image

We can test this ourselves there is no need to run this on every PR towards the repository.

.github/workflows/build.yml

@@ -5,15 +5,13 @@ on:
             - '.txt'
             - 'LICENSE'
             - 'docs/**'
+        branches: [main]
+    push:
+        branches:
+            - main
 
 jobs:
-    pr-build:
-        if: >
-            github.event_name == 'pull_request' && !github.event.pull_request.draft && (
-              github.event.action == 'opened' ||
-              github.event.action == 'reopened' ||
-              github.event.action == 'synchronize' 
-            )
+    build:
         runs-on: ${{ matrix.os }}
         strategy:
             matrix:
@@ -34,27 +32,3 @@ jobs:
                     restore-keys: ${{ runner.os }}-m2-
             -   name: Build with Maven
                 run: mvn --no-transfer-progress verify
-            -   name: "Set up QEMU"
-                if: runner.os == 'Linux'
-                uses: docker/setup-qemu-action@v2.2.0
-            -   name: "Set up Docker Buildx"
-                if: runner.os == 'Linux'
-                uses: docker/setup-buildx-action@v3
-            -   name: "Verify Docker WebGoat build"
-                if: runner.os == 'Linux'
-                uses: docker/build-push-action@v5.1.0
-                with:
-                    context: ./
-                    file: ./Dockerfile
-                    push: false
-                    build-args: |
-                        webgoat_version=${{ env.WEBGOAT_MAVEN_VERSION }}
-            -   name: "Verify Docker WebGoat desktop build"
-                uses: docker/build-push-action@v5.1.0
-                if: runner.os == 'Linux'
-                with:
-                    context: ./
-                    file: ./Dockerfile_desktop
-                    push: false
-                    build-args: |
-                        webgoat_version=${{ env.WEBGOAT_MAVEN_VERSION }}