Introduce packaging.tags

[brettcannon]

Add support for PEP 425: Compatibility Tags for Built Distributions.

Closes #83

[njsmith]

Awesome to see this moving forward :-). A few comments below.

Are you planning to switch pip over to using this?

[dstufft]

Just to set expectations, I'm probably not going to get to looking at this until Christmas-ish. It's significant new functionality and it'll take me a bit to ramp up on it.

[brettcannon]

@dstufft Thanks for the update and no problem from my end. Have a happy holidays!

[brettcannon]

OK, the PR now passes CI! Over to you, @dstufft 😁

[brettcannon]

Anything I can do to help move this forward, @dstufft ? Do you want me to break this up somewhat? I could do platform-independent stuff and then do separate PRs for Windows, Linux, and macOS if that would help get this reviewed.

[dstufft]

No, I just forgot about it. I'll take a look at it later this week. Thanks for the reminder!

[brettcannon]

I now have a use for this at work, so I'm prodding again about what I can do to help get this reviewed.

[dstufft]

Made some comments. I feel really bad about how long I left this sit, so feel free to push back on things if reworking them would require a bunch of additional effort. Overall I think the structure here is fairly reasonable.

[brettcannon]

@dstufft PTAL

[dstufft]

Awesome. This looks great ✨ Sorry that it took so long to get reviewed.

[brettcannon]

Thanks for landing this! And no problem about the time, just glad it worked out in the end.