[#8005] Update minimum release/source/target to JDK 21

Author: mattrpav

.github/workflows/build.yml

@@ -34,10 +34,10 @@ jobs:
 
     steps:
       - uses: actions/checkout@v4
-      - name: Set up JDK 17
+      - name: Set up JDK 21 
         uses: actions/setup-java@v4
         with:
-          java-version: '17'
+          java-version: '21'
           distribution: 'temurin'
       - name: Build
         run: mvn -U -B -e clean install -DskipTests -Prat

pom.xml

@@ -151,7 +151,7 @@
 
     <properties>
         <project.build.outputTimestamp>1695310533</project.build.outputTimestamp>
-        <maven.compiler.target>11</maven.compiler.target>
+        <maven.compiler.target>21</maven.compiler.target>
 
         <scm.connection>scm:git:https://gitbox.apache.org/repos/asf/karaf.git</scm.connection>
         <scm.developerConnection>scm:git:https://gitbox.apache.org/repos/asf/karaf.git</scm.developerConnection>

tooling/karaf-maven-plugin/pom.xml

@@ -372,8 +372,9 @@
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
                 <configuration>
-                    <source>1.8</source>
-                    <target>1.8</target>
+                    <release>21</release>
+                    <source>21</source>
+                    <target>21</target>
                     <maxmem>256M</maxmem>
                     <fork>${compiler.fork}</fork>
                 </configuration>