Prepare for v4.0.0 release

Bump version

Bump version to 3.5.0

Remove official support for JRuby 9.1 (9.2 is supported)

9.1 has not seen updates since 2018 afaik. This aligns with 2.4  support also.

Prepare for v2.5.0 release

Bump version to 2.0.0

Bump to v1.0.0

tag v0.6.1

tag v0.6.0