Try not installing/upgrading wheel for Cygwin CI

This is for a recent problem where "pip install -U" in the virtual
environment in a Cygwin test job seems to block indefinitely on
downloading the wheel package itself (not other packages' wheels).

Author: EliahKagan

.github/workflows/cygwin-test.yml

@@ -62,8 +62,8 @@ jobs:
 
     - name: Update PyPA packages
       run: |
-        # 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
+        # Get the latest pip, and prior to Python 3.12, setuptools.
+        python -m pip install -U pip $(pip freeze --all | grep -ow ^setuptools)
 
     - name: Install project and test dependencies
       run: |