update to 1.21, update to Gradle 8.8, update to Loom 1.7

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,7 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.5-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.8-bin.zip
 networkTimeout=10000
+validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists