Use Python 3.9.16 on Cygwin CI

.github/workflows/cygwin-test.yml

@@ -15,7 +15,7 @@ jobs:
 
     defaults:
       run:
-        shell: C:\cygwin\bin\bash.exe --login --norc -eo pipefail -o igncr "{0}"
+        shell: C:\tools\cygwin\bin\bash.exe --login --norc -eo pipefail -o igncr "{0}"
 
     steps:
     - name: Force LF line endings
@@ -27,11 +27,10 @@ jobs:
       with:
         fetch-depth: 0
 
-    - name: Install Cygwin
-      uses: cygwin/cygwin-install-action@v4
+    - name: Set up Cygwin
+      uses: egor-tensin/setup-cygwin@v4
       with:
-        packages: python38 python38-pip python38-virtualenv git
-        add-to-path: false  # No need to change $PATH outside the Cygwin environment.
+        packages: python39=3.9.16-1 python39-pip python39-virtualenv git
 
     - name: Arrange for verbose output
       run: |
@@ -55,23 +54,28 @@ jobs:
         # and cause subsequent tests to fail
         cat test/fixtures/.gitconfig >> ~/.gitconfig
 
+    - name: Ensure the "pip" command is available
+      run: |
+        # This is used unless, and before, an updated pip is installed.
+        ln -s pip3 /usr/bin/pip
+
     - name: Update PyPA packages
       run: |
-        # Get the latest pip, setuptools, and wheel.
-        python3.8 -m pip install -U pip setuptools wheel
+        # Get the latest pip, wheel, and prior to Python 3.12, setuptools.
+        python -m pip install -U pip $(pip freeze --all | grep -ow ^setuptools) wheel
 
     - name: Install project and test dependencies
       run: |
-        python3.8 -m pip install ".[test]"
+        pip install ".[test]"
 
     - name: Show version and platform information
       run: |
         uname -a
-        command -v git python3.8
+        command -v git python
         git version
-        python3.8 --version
-        python3.8 -c 'import os, sys; print(f"sys.platform={sys.platform!r}, os.name={os.name!r}")'
+        python --version
+        python -c 'import os, sys; print(f"sys.platform={sys.platform!r}, os.name={os.name!r}")'
 
     - name: Test with pytest
       run: |
-        python3.8 -m pytest --color=yes -p no:sugar --instafail -vv
+        pytest --color=yes -p no:sugar --instafail -vv