Pin pytest to a version supporting Python 2

Run "pytest", not "py.test"

Author: srittau

.github/workflows/ci.yml

@@ -37,11 +37,11 @@ jobs:
           PYTHON_VERSION: ${{ matrix.python-version }}
         run: |
           export PYTHONPATH=`python -c "import sys; print('python2' if sys.version.startswith('2') else 'src')"`
-          if [[ $PYTHON_VERSION < '3.7' ]]; then py.test $PYTHONPATH; fi
+          if [[ $PYTHON_VERSION < '3.7' ]]; then pytest $PYTHONPATH; fi
 
           if [[ $PYTHON_VERSION < '3.5' ]]; then pip install -U .; fi
           export PYTHONPATH=`python -c "import sys; print('typing_extensions/src_py2' if sys.version.startswith('2') else 'typing_extensions/src_py3')"`
-          py.test $PYTHONPATH
+          pytest $PYTHONPATH
 
   linting:
     name: Run linting

test-requirements.txt

@@ -1,6 +1,6 @@
 flake8; python_version >= '3.6'
 flake8-bugbear; python_version >= '3.6'
 flake8-pyi; python_version >= '3.6'
-pytest>=4.4.1; python_version >= '3.4'
+pytest==4.6.11
 pytest-xdist>=1.18; python_version >= '3.4'
 pytest-cov>=2.4.0; python_version >= '3.4'