Upgrade pip, as the tests now practically depend on pip >= 25.1

Author: stefanor

.github/workflows/ci.yaml

@@ -298,7 +298,7 @@ jobs:
         CIBW_MUSLLINUX_AARCH64_IMAGE: ${{ matrix.musllinux_img || 'musllinux_1_1' }}
         CIBW_PRERELEASE_PYTHONS: 'True'
         CIBW_FREE_THREADED_SUPPORT: 'True'
-        CIBW_TEST_REQUIRES: pytest setuptools  # 3.12+ no longer includes distutils, just always ensure setuptools is present
+        CIBW_TEST_REQUIRES: pytest setuptools pip>=25.1  # 3.12+ no longer includes distutils, just always ensure setuptools is present
         CIBW_TEST_COMMAND: PYTHONUNBUFFERED=1 python -m pytest ${{ matrix.test_args || '{project}' }}  # default to test all
       run: |
         set -eux

testing/cffi0/test_zintegration.py

@@ -32,6 +32,7 @@ def create_venv(name):
                 '-m',
                 'pip',
                 'install',
+                'pip',
                 'setuptools',
                 '--upgrade'
             ])