Upgrate gradle version to 7.6

[HomeOfTheWizard]

Update gradle version from 5.4.0 to 7.6.1 🚀 Remove deprecated APIs and replace them (see doc for details):

• [x] change testCompile to testImplementation
• [x] apply syntax for plugins
• [x] replace task classifier with archiveClassifier (see here)
• [x] test tasks and configuration (see here)
• [x] replace maven plugin with maven-publish plugin (see here)

[henryx]

Thank you so much of the PR, I'll merge it ASAP