Prerelease does not Respect Default_Bump

Nobody has claimed this yet.

When having `default_bump=minor` I would expect a prerelease to do a minor update when creating the prerelease version. Currently it always does a patch update.

E.g.
latest release is `1.2.3`, I would expect an execution of the action on a branch basing from that version, with parameters `default_bump=minor` and `default_prerelease_bump=prerelease` to generate the version `1.3.0-beta.0`, since 1.3.0 is the version the final release will (most likely) be.
Instead, it currently generates the version `1.2.4-beta.0`, which is a patch increase.

Another run on top should then do the correct prerelease update to create version `1.3.0-beta.1`

I think adjustments need to address the code starting at
https://github.com/mathieudutour/github-tag-action/blob/e923a6115f1a2ccc3404e26ec2535092a9fd5536/src/action.ts#L155

You could argue that this is a bug/feature of semver itself, but it really is relating to correctly interpreting default actions which is responsibility of this module, not semver.

Start in src/action.ts around line 155 and reproduce the action with default_bump=minor and default_prerelease_bump=prerelease from version 1.2.3. The fix is done when the first prerelease is 1.3.0-beta.0 and a subsequent run produces 1.3.0-beta.1 rather than patch-based versions.

Written by the indexing model from the issue text.