Drop use of setup-python's cache: pip

Suddenly started causing errors like the following in the pypy-3.10 job:

    Cache folder path is retrieved for pip but doesn't exist on disk: /home/runner/.cache/pip

Ref: https://github.com/jab/bidict/actions/runs/10752803825/job/29821540586

It's superfluous now that setup-cached-uv is used anyway.

.github/workflows/benchmark.yml

@@ -38,8 +38,6 @@ jobs:
           # When upgrading to a new Python version, remember to upload new associated baseline
           # benchmark results here: https://github.com/jab/bidict/releases/edit/microbenchmarks
           python-version: '3.12.2'
-          cache: pip
-          cache-dependency-path: dev-deps/test.txt
       - name: set up cached uv
         uses: hynek/setup-cached-uv@4b4bfa932036976749a9653b0fa4fa10b1a7092b
       - name: create and activate virtualenv

.github/workflows/test.yml

@@ -51,8 +51,6 @@ jobs:
         uses: actions/setup-python@82c7e631bb3cdc910f68e0081d67478d79c6982d
         with:
           python-version: ${{ matrix.pyversion }}
-          cache: pip
-          cache-dependency-path: dev-deps/test.txt
       - name: set up cached uv
         uses: hynek/setup-cached-uv@4b4bfa932036976749a9653b0fa4fa10b1a7092b
       - name: create and activate virtualenv