fix(maintainer): drop pip cache from setup-python

[ianlintner]

The thin streaming Caretaker workflow has no actions/checkout step, so actions/setup-python@v5 with cache: "pip" errors out before pip ever runs:

##[error]No file in /home/runner/work/<repo>/<repo> matched to [**/requirements.txt or **/pyproject.toml], make sure you have checked out the target repository

Drop the line. The thin client installs exactly one wheel (caretaker) per scheduled run; pip caching adds negligible value, and adding a checkout / synthetic dependency file purely to enable cache would be more code for no benefit.

The upstream template was fixed in ianlintner/caretaker#636. This PR ports the same one-line change to the deployed copy in this repo, since caretaker's bootstrap agent only writes templates on initial install.

🤖 Generated with Claude Code

[care-taker-bot]

@claude caretaker is requesting a full code review for this PR.

Repo: ianlintner/python_dsa · PR: #65
Routing reason: score=23 [sensitive_files(+23)] → inline

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