Update CI (#280)

Add Java21 to matrix, set up concurrency (and drop use of deprecated action). Update invoker as well.

.github/workflows/ci.yml

@@ -6,21 +6,16 @@ on:
       - master
   pull_request:
 
-jobs:
-  setup:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Stop old builds
-        if: github.ref != 'refs/heads/master'
-        uses: styfle/cancel-workflow-action@0.11.0
-        with:
-          access_token: ${{ github.token }}
+concurrency: 
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
 
+jobs:
   build:
-    needs: setup
     strategy:
       matrix:
-        java: [ 8, 11, 17 ]
+        java: [ 8, 11, 17, 21 ]
+      fail-fast: false
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
@@ -30,4 +25,5 @@ jobs:
           java-version: ${{ matrix.java }}
           distribution: 'temurin'
       - name: Build & Test
-        run: ./mvnw -B verify
+        run: ./mvnw -B clean verify
+

pom.xml

@@ -223,7 +223,10 @@
       <plugins>
         <plugin>
           <artifactId>maven-invoker-plugin</artifactId>
-          <version>3.4.0</version>
+          <version>3.6.0</version>
+          <configuration>
+            <scope>test</scope>
+          </configuration>
         </plugin>
         <plugin>
           <artifactId>maven-release-plugin</artifactId>