Upgrade to Gradle 7.6 and Kotlin 1.7

[philipp94831]

No description provided.

[torbsto]

This might require switching to https://github.com/gradle-nexus/publish-plugin, because https://github.com/Codearte/gradle-nexus-staging-plugin/ and https://github.com/Codearte/gradle-nexus-staging-plugin/ are deprecated in favor of it and therefore, it is possible that they are not compatible with the newest Kotlin and Gradle versions

[raminqaf]

There is a good Migration guide that we can use: https://github.com/gradle-nexus/publish-plugin/wiki/Migration-from-gradle_nexus_staging-plugin---nexus_publish-plugin-duo

[philipp94831]

Managed to upgrade to 7.2. Further updates are blocked due to #43 (comment)