[ANNOUNCE] GMavenPlus 3.0.0

Bugs

   - [#244 <https://github.com/groovy/GMavenPlus/issues/244>] Fix Maven
   plugin validation warnings.

Enhancements

   - [#239 <https://github.com/groovy/GMavenPlus/issues/239>] Require Maven
   3.2.5.

Potentially breaking changes

Maven's compatibility plan
<https://maven.apache.org/developers/compatibility-plan.html> marked Maven
versions older than 3.2.5 as EOL in March 2023. Therefore, we now require
3.2.5 to move forward with the rest of the ecosystem.
Notes

Fixing the validation warnings removed some Maven dependencies from the
plugin's classpath (instead of using the ones from Maven itself). I'm not
aware of any negative consequences of this, but it's possible certain
specialized use cases might encounter changes in behavior.