Added Java8 build step

Author: egonw

.github/workflows/build.yml

@@ -7,8 +7,21 @@ on:
     branches: [ series/3.1.0 ]
 
 jobs:
-  build:
+  java8:
+    runs-on: ubuntu-latest
 
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up Java
+      uses: actions/setup-java@v4
+      with:
+        distribution: 'temurin'
+        java-version: 8
+        cache: maven
+    - name: Build with Maven
+      run: mvn -f pom-java8.xml clean install -Dgpg.skip -Dmaven.javadoc.skip=true -Dmaven.test.failure.ignore=true -Dproject.build.sourceEncoding=UTF-8 -Djunit5.excludeGroups=webservice,mysql
+
+  build:
     runs-on: ubuntu-latest
 
     steps: