Play Framework

ci(build-test): drop broken pip cache/install for removed requirements.txt

f6c38bb87 removed python/requirements.txt (its only deps were for the
deleted i-am-a-developer integration tests) but build-test.yml was
never updated to match. setup-python@v6 now errors hard when
cache-dependency-path: '**/requirements.txt' matches no files, and
the subsequent 'pip install -r python/requirements.txt' would fail
on a missing file. Drop both from the testing and build-on-mac jobs.

setup-python itself stays — ant test still shells out to the Python
play CLI for sample-app functional tests; that script has no pip
dependencies.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>