chore: Test against Gradle v9

Testing against latest milestone of v9

Author: ajoberstar

grgit-gradle/stutter.lockfile

@@ -1,4 +1,4 @@
 # DO NOT MODIFY: Generated by Stutter plugin.
-java11=7.0.2,7.6.4,8.0.2,8.10.2
-java17=7.3.3,7.6.4,8.0.2,8.10.2
-java21=8.4,8.10.2
+java11=7.0.2,7.6.5,8.0.2,8.14.2,9.0.0-milestone-9
+java17=7.3.3,7.6.5,8.0.2,8.14.2,9.0.0-milestone-9
+java21=8.4,8.14.2,9.0.0-milestone-9