Add Workflow for main branch

The main branch requires a different build:

- use JDK 11
- separate clean & verify Maven command

Signed-off-by: Karsten Schnitter <k.schnitter@sap.com>

Author: KarstenSchnitter

.github/workflows/maven-verify.yml

@@ -3,10 +3,27 @@ name: Maven Verify
 on:
   pull_request:
     branches:
+      - main
       - release-4
 
 jobs:
-  build:
+  build-main:
+    if: github.base_ref == 'main'
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up JDK 11
+        uses: actions/setup-java@v4
+        with:
+          distribution: 'temurin'
+          java-version: '11'
+      - name: Clean with Maven
+        run: mvn clean
+      - name: Build with Maven
+        run: mvn verify
+
+  build-releas-4:
+    if: github.base_ref == 'release-4'
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4