Use the 'release-branch-semver' version scheme for setuptools_scm

[seisman]

See #3828 for the original issue report.

Upstream explainations at https://setuptools-scm.readthedocs.io/en/latest/extending/#setuptools_scmversion_scheme.

Semantic versioning for projects with release branches. The same as guess-next-dev (incrementing the pre-release or micro segment) however when on a release branch: a branch whose name (ignoring namespace) parses as a version that matches the most recent tag up to the minor segment. Otherwise if on a non-release branch, increments the minor segment and sets the micro segment to zero, then appends .devN

With the release-branch-semver version scheme, the next dev version is v0.15.0.dev0 rather than v0.14.1.dev0 after we release v0.14.0.

[seisman]

@weiji14 Hopefully you have time to review this PR and issue #3826, since you may have more experience with package versioning.

[weiji14]

Sorry for the late reply, too much work+travel during the past two weeks. Using release-branch-semver seems ok, having v0.15.0.devX as the next dev version instead of v0.14.1.devX makes sense, given that PyGMT doesn't do patch releases that often.