Backport PR #13505: try to fix Appveyor

appveyor.yml

@@ -1,31 +1,31 b''
 build: false
 matrix:
   fast_finish: true     # immediately finish build once one of the jobs fails.
 
 environment:
   matrix:
 
    - PYTHON: "C:\\Python37-x64"
      PYTHON_VERSION: "3.7.x"
      PYTHON_ARCH: "64"
 
    - PYTHON: "C:\\Python38"
      PYTHON_VERSION: "3.8.x"
      PYTHON_ARCH: "32"
 
    - PYTHON: "C:\\Python38-x64"
      PYTHON_VERSION: "3.8.x"
      PYTHON_ARCH: "64"
 
 init:
   - "ECHO %PYTHON% %PYTHON_VERSION% %PYTHON_ARCH%"
 
 install:
   - "SET PATH=%PYTHON%;%PYTHON%\\Scripts;%PATH%"
-  - "%CMD_IN_ENV%  python -m pip install --upgrade setuptools pip"
+  - "%CMD_IN_ENV%  python -m pip install --upgrade setuptools pip<22"
   - "%CMD_IN_ENV%  pip install nose coverage pytest"
   - "%CMD_IN_ENV%  pip install .[test]"
   - "%CMD_IN_ENV%  mkdir results"
   - "%CMD_IN_ENV%  cd results"
 test_script:
   - "%CMD_IN_ENV%  iptest --coverage xml"