Improve Release Handling

[programming-wolf]

• Update to most recent official Gradle build action
• Read release version from system environment. If it is not set, use "LocalBuild" instead
• Use checked-in Gradle Wrapper, no more updates to workflow files required if we upgrade Gradle

And it works: https://github.com/isaqb-org/advanced-template/releases/tag/2020.7-RC1

close #132