v2 no longer downloads tags

[charliebruce]

As of v2, tags are no longer available in the cloned repository, whereas previously tags would have been visible. I was caught out by this, as I was referencing this Action by @master rather than @v1.

Worth mentioning somewhere in the changelog?

[ericsciple]

i'll update the scenarios in the readme. v2 perf was optimized for the mainline scenario, and only fetches a single commit

[gitfool]

Rather than now requiring a separate run command to fetch tags, it would be much nicer to have a fetch-tags option. Default to false to preserve new behaviour, passing --no-tags, otherwise pass --tags when true.