Check each repo has a tag for the used crate version

[jayvdb]

It is all too common for repos to not add a tag for a crate release.

It would be great if this tool could issue a warning if the repo doesnt have a tag to match the crate version in my lock file.

This check can also be used to assist with problems like #441 and #606 to check when the repo contained the crate, if it currently doesnt contain the crate.

[smoelius]

In your mind, should this check be performed for all packages, or just the ones considered unmaintained?

[jayvdb]

IMO this would be useful if performed for all packages, at least those hosted on github.