Ruby versioning has incompatible with semver #25

• PRERELEASE GEMS
• Semantic Versioning 2.0.0

Ruby's pre-release is period separated, e.g. 1.2.3.pre or 2.3.4.beta.1.
Semver pre-release is hyphen separated.
E.g Example: 1.0.0-alpha < 1.0.0-alpha.1 < 1.0.0-alpha.beta < 1.0.0-beta < 1.0.0-beta.2 < 1.0.0-beta.11 < 1.0.0-rc.1 < 1.0.0.

I write 1.0.0-rc.1, then parse_gemspec (and ruby) recognize this as 1.0.0.pre.rc.1.
1.0.0.pre.rc.1 is not compatible with semver, so this brings

TypeError: Error in conventional-changelog-writer: Invalid Version: 1.0.0.pre.rc.1