fix: remove `clone` strategy

It should be entirely up to the user to decide the strategy.

The default of `fetch` is significantly faster for large projects.

A default of `clone` will be a regression for those projects.

The only time a full clone is needed is if one has deleted a tag and
the remote CI has cached that tag in the fetch. This is easy to fix
by switching over the CI settings to clone for a single run or adding
a `GIT_STRATEGY` CI variable for a short period to clean out the cache.