Top-level LICENSE says Gradle wrapper v5.5, but the gradlew scripts are from Gradle 6.9.1 #269

The top-level LICENSE (line 229 in the 0.9.0-incubating-RC7 source release) says:

Gradle wrapper v5.5
  The files build/openwhisk/gradlew and build/openwhisk/gradlew.bat are
  distributed under the Apache License, Version 2.0. For details see those
  files.

The shipped gradlew and gradlew.bat are not from Gradle 5.5. They are the wrapper scripts from Gradle 6.9.x (6.9.1).

Evidence

• build/openwhisk/gradlew is byte-identical to upstream Apache OpenWhisk's gradlew as of commit f29981a2f "Bumping to gradle 6" (2022-07-28). gradlew.bat is identical to that commit's too, apart from CRLF line endings. That commit set the wrapper to gradle-6.9.1-bin.zip.
• The Gradle 5.5 scripts are different. OpenWhisk's scripts from d9de97d6e "Update Gradle to 5.5 version" (2019), which match Gradle's own v5.5.0 scripts, do not match what we ship.
• Compared with the gradlew in Gradle's own repository at v6.9.1, ours differs only in DEFAULT_JVM_OPTS: Gradle's own build adds -Dfile.encoding=UTF-8, which is project-specific.
• The rest of the build agrees: build/openwhisk/gradle/wrapper/gradle-wrapper.properties uses gradle-6.9.1-bin.zip, and build/Taskfile.yml downloads the 6.9.1 gradle-wrapper.jar.

The "v5.5" text was inherited from upstream OpenWhisk's LICENSE.txt, which was not updated when OpenWhisk moved to Gradle 6.

Suggested fix

Change the top-level LICENSE entry to Gradle 6.9.1, e.g.:

Gradle wrapper v6.9.1
  The files build/openwhisk/gradlew and build/openwhisk/gradlew.bat are
  distributed under the Apache License, Version 2.0. For details see those
  files.

The same "v5.5" text also appears in build/LICENSE, build/NOTICE, oplugins-op/LICENSE and build/openwhisk/LICENSE.txt. That is another example of the subdirectory copies drifting (#268). oplugins-op/LICENSE is also wrong in a second way: oplugins-op contains no gradlew at all.

Related: #268.