Build and upload Python 3.13 wheel

[justin-omalley]

Description

Adds Python 3.13.12 to the build_wheel matrix alongside 3.12.6, so we start publishing cp313 wheels. This is a prerequisite for upgrading servers to Python 3.13.

Also pins the uv build interpreter to the matrix Python version. uv build ignores the activated venv and uses the newest Python installed on the runner, which only worked before because a single version was installed; with two versions in the matrix, both jobs would otherwise build cp313 wheels.

Jira, Podio Bug or Trello Card Link:

https://everlaw.atlassian.net/browse/PE-791

Testing Procedure or Link:

• build_wheel workflow runs on this branch and both matrix jobs (3.12.6 and 3.13.12) pass, including the import fasttext wheel check
• fasttext-0.9.5-cp313-cp313-linux_x86_64.whl (and .sig) appear in s3://everlaw-artifacts/fasttext/
• The 3.12 job reports "already exists" for the current cp312 wheel and does not fail

Link to SIA (N/A if None):

N/A