test-bot: install brewed curl if needed

[iMichka]

This is needed when using brewed curl to fetch and/or audit
formulae

See Homebrew/brew#11705

[request-info]

Please provide a better issue/pull request title and/or description!

[iMichka]

error: could not lock config file .git/config: Permission denied
Error: Command failed with exit 255: git

[iMichka]

This is ready for review. @MikeMcQuaid is there a place where I can ask it to uninstall curl when the tests are done?

[iMichka]

I merged this to test the change in homebrew-core. We can't use the new :using strategy before a new brew release is made anyway, so we have a little bit of time.

I would still want to explore the possibility to uninstall brewed curl at the end of the test run of each formula.

[MikeMcQuaid]

I would still want to explore the possibility to uninstall brewed curl at the end of the test run of each formula.

@iMichka I think this should happen automatically with the existing code.