build(groovy): upgrade Groovy to 4.0.31 for JDK 25

The Groovy 4.0.24 compiler cannot process Java 25 class files (fails with
"Unsupported class file major version 69") when compiling tests on the
Java 25 toolchain. Bump to 4.0.31, which supports JDK 25, matching the
version used by the nextflow project.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: Cristian Ramon-Cortes <cristian.ramon-cortes@seqera.io>

Author: cristianrcv

app/build.gradle

@@ -32,10 +32,10 @@ dependencies {
     // bump commons-io version to address security vulnerabilities
     runtimeOnly 'commons-io:commons-io:2.18.0'
 
-    testImplementation "org.apache.groovy:groovy:4.0.24"
-    testImplementation "org.apache.groovy:groovy-nio:4.0.24"
-    testImplementation "org.apache.groovy:groovy-test:4.0.24"
-    testImplementation "org.apache.groovy:groovy-json:4.0.24"
+    testImplementation "org.apache.groovy:groovy:4.0.31"
+    testImplementation "org.apache.groovy:groovy-nio:4.0.31"
+    testImplementation "org.apache.groovy:groovy-test:4.0.31"
+    testImplementation "org.apache.groovy:groovy-json:4.0.31"
     testImplementation "net.bytebuddy:byte-buddy:1.14.11"
     testImplementation ("org.spockframework:spock-core:2.4-groovy-4.0") { exclude group: 'org.apache.groovy' }
 }