Support zstd on Android

[mhsmith]

Feature or enhancement

As seen on the buildbot, it's currently being omitted:

checking for libzstd >= 1.4.5... no

In the current build system, this will require the following:

• Add a libzstd release in https://github.com/beeware/cpython-android-source-deps.
• Update android.py to download it before running configure.

Related:

• Add libzstd to apple source deps beeware/cpython-apple-source-deps#60

Linked PRs

• gh-135846: Add zstd dependency to Android build script #136253
• [3.14] gh-135846: Add zstd dependency to Android build script (GH-136253) #136491

[picnixz]

@emmatyping anything else to do?

[emmatyping]

I believe this can be closed!