Merge pull request #120 from nextflow-io/fix/java-21-support

Fix compile issues in java 21+

Author: nvnieuwk

.github/workflows/build.yml

@@ -17,7 +17,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        java_version: [11, 17]
+        java_version: [11, 17, 21]
 
     steps:
       - name: Environment

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.6-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.13-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists