Function calculate_new_version 

pub fn calculate_new_version(
    current: &Version,
    bump_type: Option<BumpType>,
    prerelease: Option<&PrereleaseSpec>,
) -> Result<Version, VersionError>

Calculates a new version based on bump type and optional prerelease spec.

Errors

Returns VersionError::InvalidPrerelease if the prerelease identifier produces an invalid semver prerelease string.