fix(git): optimize fetch to selectively include tags and checkout exct

[corydolphin]

This is a continuation of https://github.com/carvel-dev/vendir/pull/427 simply with an additional stacked diff to address lint failures.

Hello,

I've enjoyed using this tool and would benefit from @fpytloun's tag fetching changes. I've made a quick change to hopefully fix the lint errors, and it seems to pass all tests locally.

I don't seem to be able to more easily stack these changes with a PR on top of @fpytloun's work, so this is a new PR.

Thank you, Cory

[fpytloun]

Thank you @corydolphin, I did not have time to work on my PR further.