feat: upgrade maven and gradle plugins

Upgrade maven and gradle plugins to newest versions, which among other
changes include printing part of the stack trace for reachability
analysis as well as some quality of life fixes.

package.json

@@ -79,9 +79,9 @@
     "snyk-cpp-plugin": "2.0.0",
     "snyk-docker-plugin": "3.24.0",
     "snyk-go-plugin": "1.16.2",
-    "snyk-gradle-plugin": "3.7.0",
+    "snyk-gradle-plugin": "3.8.0",
     "snyk-module": "3.1.0",
-    "snyk-mvn-plugin": "2.19.4",
+    "snyk-mvn-plugin": "2.21.1",
     "snyk-nodejs-lockfile-parser": "1.28.1",
     "snyk-nuget-plugin": "1.19.3",
     "snyk-php-plugin": "1.9.2",