Add support for shallow clones

[CraZySacX]

• Added shallow clone support to TestRepos
• Added check for shallow clone to gix

Fixes #250

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (a8556fc) 97.76% compared to head (e7aff15) 97.96%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #288 +/- ## ========================================== + Coverage 97.76% 97.96% +0.19% ========================================== Files 24 24 Lines 1613 1622 +9 ========================================== + Hits 1577 1589 +12 + Misses 36 33 -3 ```

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