Also install a Java 17 build chain for Gradle

Author: gsmet

.github/matrix-jvm-tests.json

@@ -12,6 +12,7 @@
         "name": "JVM Tests - JDK 21",
         "category": "Runtime",
         "java-version": 21,
+        "java-version-gradle": 17,
         "maven_args": "$JVM_TEST_MAVEN_ARGS",
         "maven_opts": "-Xmx3g -XX:MaxMetaspaceSize=1g",
         "os-name": "ubuntu-latest",
@@ -21,6 +22,7 @@
         "name": "JVM Tests - JDK 25",
         "category": "Runtime",
         "java-version": 25,
+        "java-version-gradle": 17,
         "maven_args": "$JVM_TEST_MAVEN_ARGS",
         "maven_opts": "-Xmx3g -XX:MaxMetaspaceSize=1g",
         "os-name": "ubuntu-latest",