Updating gradle in OpenJFX:

1. Update jfx.gradle.version in build.properties

NOTE: only update the minimum when necessary (e.g., when replacing deprecated APIs in preparation for updating to a major version of gradle)


2. Update gradle wrapper:

* Update the version number in the URL in gradle/wrapper/gradle-wrapper.properties
* Run: bash gradlew wrapper --gradle-version VERSION
* Verify the changes (fix line endings in gradlew.bat if needed)
* Add "distributionSha256Sum" back into gradle/wrapper/gradle-wrapper.properties (get the checksum from https://gradle.org/release-checksums)
