Try giving IPv4 for files.pythonhosted.org in hosts file

Author: EliahKagan

.github/workflows/cygwin-test.yml

@@ -30,14 +30,22 @@ jobs:
     - name: Install Cygwin
       uses: cygwin/cygwin-install-action@v4
       with:
-        packages: python39 git
+        packages: python39 python39-pip python39-virtualenv git
         add-to-path: false  # No need to change $PATH outside the Cygwin environment.
 
     - name: Arrange for verbose output
       run: |
         # Arrange for verbose output but without shell environment setup details.
         echo 'set -x' >~/.bash_profile
 
+    - name: Add PyPI hosts file entry  # NOTE: Actually edits the Windows hosts file.
+      run: |
+        echo '199.232.96.223 files.pythonhosted.org' >>/etc/hosts
+
+    - name: Show hosts file
+      run: |
+        cat /etc/hosts
+
     - name: Special configuration for Cygwin git
       run: |
         git config --global --add safe.directory "$(pwd)"
@@ -55,14 +63,19 @@ 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, wheel, and prior to Python 3.12, setuptools.
-        python -m pip install -U pip $(python -m pip freeze --all | grep -ow ^setuptools) wheel
+        python -m pip install -U pip $(pip freeze --all | grep -ow ^setuptools) wheel
 
     - name: Install project and test dependencies
       run: |
-        python -m pip install ".[test]"
+        pip install ".[test]"
 
     - name: Show version and platform information
       run: |