try to fix app-veyor

appveyor.yml

@@ -1,27 +1,27 b''
 build: false
 matrix:
   fast_finish: true     # immediately finish build once one of the jobs fails.
 
 environment:
   global:
     APPVEYOR_BUILD_WORKER_IMAGE: 'Visual Studio 2022'
     COLUMNS: 120  # Appveyor web viwer window width is 130 chars
 
   matrix:
    - PYTHON: "C:\\Python38"
      PYTHON_VERSION: "3.8.x"
      PYTHON_ARCH: "32"
 
 init:
   - "ECHO %PYTHON% %PYTHON_VERSION% %PYTHON_ARCH%"
 
 install:
   - "SET PATH=%PYTHON%;%PYTHON%\\Scripts;%PATH%"
-  - python -m pip install --upgrade setuptools pip
+  - python -m pip install --upgrade setuptools 'pip<22'
   - pip install pytest-cov
   - pip install -e .[test_extra]
 test_script:
   - pytest --color=yes -ra --cov --cov-report=xml
 on_finish:
   - curl -Os https://uploader.codecov.io/latest/windows/codecov.exe
   - codecov -e PYTHON_VERSION,PYTHON_ARCH