Pex

This release adds tools to interact with Pex's new embedded offline
documentation. You can browse those docs with `pex --docs` or, more
flexibly, with `pex3 docs`. See `pex3 docs --help` for all the options
available.

This release also returns to [SemVer](https://semver.org/) versioning
practices. Simply, you can expect 3 things from Pex version numbers:

+ The first component (the major version) will remain 2 as long as
possible. Pex tries very hard to never break existing users and to
allow them to upgrade without fear of breaking. This includes not
breaking Python compatibility. In Pex 2, Python 2.7 is supported as
well as Python 3.5+ for both CPython and PyPy. Pex will only continue
to add support for new CPython and PyPy releases and never remove
support for already supported Python versions while the major version
remains 2.
+ The second component (the minor version) will be incremented whenever
a release adds a feature. Since Pex is a command line tool only (not
a library), this means you can expect a new subcommand, a new option,
or a new allowable option value was added. Bugs might also have been
fixed.
+ The third component (the patch version) indicates only bugs were
fixed.

You can expect the minor version to get pretty big going forward!

* Add `pex --docs` and several `pex3 docs` options. (2365)

This release moves Pex documentation from https://pex.readthedocs.io to
https://docs.pex-tool.org. While legacy versioned docs will remain
available at RTD in perpetuity, going forward only the latest Pex
release docs will be available online at the https://docs.pex-tool.org
site. If you want to see the Pex docs for the version you are currently
using, Pex now supports the `pex3 docs` command which will serve the
docs for your Pex version locally, offline, but with full functionality,
including search.

* Re-work Pex documentation. (2362)

This release fixes Pex to work in certain OS / SSL environments where it
did not previously. In particular, under certain Fedora distributions
using certain Python Build Standalone interpreters.

* Create SSLContexts in the main thread. (2356)

This release adds support for `--pip-version 24.0` as well as fixing a
bug in URL encoding for artifacts in lock files. Notably, torch's use of
local version identifiers (`+cpu`) combined with their find links page
at https://download.pytorch.org/whl/torch_stable.html would lead to
`pex3 lock create` errors.

* Add support for Pip 24.0. (2350)
* Fix URL escaping for lock artifacts. (2349)

This release adds support for `--only-wheel <project name>` and
`--only-build <project name>` to allow finer control over which
distribution artifacts are resolved when building a PEX or creating or
updating a lock file. These options correspond to Pip's `--only-binary`
and `--no-binary` options with project name arguments.

* Plumb Pip's `--{no,only}-binary`. (2346)

This release adds the ability for `pex3 lock update` to replace
requirements in a lock or delete them from the lock using
`-R` / `--replace-project` and `-d` / `--delete-project`, respectively.

* Lock updates support deleting & replacing reqs. (2335)