Issue-2002 (wrong calculation of pre-release version)

[pi3k14]

Created unit test

using var fixture = new EmptyRepositoryFixture();
fixture.Repository.MakeACommit();
fixture.BranchTo("develop");
fixture.MakeATaggedCommit("1.0.0-alpha.3"); // manual bump version
fixture.MakeACommit();
fixture.MakeACommit();
fixture.AssertFullSemver("1.0.0-alpha.5");

Fixes #2002.

[asbjornu]

Thank you so much for your contributions, @pi3k14! 🙏

[jetersen]

I would love to test the prerelase, yet publish failed: https://dev.azure.com/GitTools/GitVersion/_build/results?buildId=1595&view=results
Edit: seems like it managed to publish anyhow