devel/gradle: Update to 6.0.1

• Assign to myself

Changes: https://docs.gradle.org/6.0.1/release-notes.html
PR: 239875
Submitted by: Radim Kolar <hsn@sendmail.cz> (update to 5.6)
Approved by: gasol.wu@gmail.com (maintainer timeout, 3 months)