Resolve "Improved automated release flow"

Partially resolves #104 (closed)

Changes in this update:

1. Prerelease is now a manual step, which can be kicked off by clicking the job in any created pipeline.
   • A prerelease requires no additional prep work, and can be cut against any successful Gitlab pipeline.
2. Releases are published to pypi and cut on gitlab by creating a tag named vX.Y.Z. The tag name must exactly match the pyproject.toml version number of X.Y.Z.
   • A mismatch between tag name and version number will raise this error in the Gitlab pipeline: ERROR - Tag 'test-tag3' did not match detected version 'v0.1.2'.
3. Changelog and project version must be prepped manually prior to creating the release tag.