Release 2.0.0

[jsirois]

On the docket:

• Use pip for resolving and building distributions. Use pip for resolving and building distributions. #788
• Pex defaults to reproduceable builds. Pex defaults to reproduceable builds. #791

That one issue closes out a slew of others, partially documented in #686.

[Eric-Arellano]

Do we still want to flip the defaults to be --no-use-system-time and --no-compile for reproducible PEXes by default?

See the PR description #722 (comment), which claims:

We will default to --use-system-time for now to keep prior behavior, and then in a future release like 1.70 will switch over to default to reproducible builds.

This decision was made in #718.

[jsirois]

Do we still want to flip the defaults to be --no-use-system-time and --no-compile for reproducible PEXes by default?

Sounds good. I'll send up a small PR for that presently.