Use *-wheel packages as a better fix for #2004

This installs the `python-pip-wheel`, `python-setuptools-wheel`,
and `python-wheel-wheel` packages on Cygwini CI, which provide
`.whl` files for `pip`, `setuptools`, and `wheel`.

By making those wheels available, this fixes #2004 better than the
previous workaround, allowing `ensurepip` to run without the error:

    Traceback (most recent call last):
      File "/usr/lib/python3.9/runpy.py", line 188, in _run_module_as_main
        mod_name, mod_spec, code = _get_module_details(mod_name, _Error)
      File "/usr/lib/python3.9/runpy.py", line 147, in _get_module_details
        return _get_module_details(pkg_main_name, error)
      File "/usr/lib/python3.9/runpy.py", line 111, in _get_module_details
        __import__(pkg_name)
      File "/usr/lib/python3.9/ensurepip/__init__.py", line [30](https://github.com/EliahKagan/GitPython/actions/runs/13454947366/job/37596811693#step:10:31), in <module>
        _SETUPTOOLS_VERSION = _get_most_recent_wheel_version("setuptools")
      File "/usr/lib/python3.9/ensurepip/__init__.py", line 27, in _get_most_recent_wheel_version
        return str(max(_wheels[pkg], key=distutils.version.LooseVersion))
    ValueError: max() arg is an empty sequence

This change takes the place of the main changes in #2007 and #2009.
In particular, it should allow `test_installation` to pass again.

This also delists non-wheel Cygwin packages such as `python39-pip`,
which are not needed (or at least no longer needed).

(The python-{pip,setuptools,wheel}-wheel packages are, as their
names suggest, intentionally not specific to Python 3.9. However,
this technique will not necessarily carry over to Python 3.12,
depending on what versions are supplied and other factors. This may
be relevant when another attempt like #1988 is made to test/support
Python 3.12 on Cygwin. At least for now, though, this seems
worthwhile for fixing the Cygwin 3.9 environment, making it more
similar to working local Cygwin environments and letting the
workflow be more usable as guidance to how to set up a local Cygwin
environment for GitPython development, and letting the installation
test pass automatically.)

Author: EliahKagan

.github/workflows/cygwin-test.yml

@@ -41,7 +41,7 @@ jobs:
     - name: Install Cygwin
       uses: cygwin/cygwin-install-action@v5
       with:
-        packages: python39 python39-pip python39-virtualenv git wget
+        packages: git python39 python-pip-wheel python-setuptools-wheel python-wheel-wheel
         add-to-path: false  # No need to change $PATH outside the Cygwin environment.
 
     - name: Arrange for verbose output
@@ -69,13 +69,9 @@ jobs:
 
     - name: Set up virtual environment
       run: |
-        python3.9 -m venv --without-pip .venv
+        python3.9 -m venv .venv
         echo 'BASH_ENV=.venv/bin/activate' >>"$GITHUB_ENV"
 
-    - name: Bootstrap pip in virtualenv
-      run: |
-        wget -qO- https://bootstrap.pypa.io/get-pip.py | python
-
     - name: Update PyPA packages
       run: |
         python -m pip install -U pip 'setuptools; python_version<"3.12"' wheel

test/test_installation.py

@@ -4,19 +4,11 @@
 import ast
 import os
 import subprocess
-import sys
-
-import pytest
 
 from test.lib import TestBase, VirtualEnvironment, with_rw_directory
 
 
 class TestInstallation(TestBase):
-    @pytest.mark.xfail(
-        sys.platform == "cygwin" and "CI" in os.environ,
-        reason="Trouble with pip on Cygwin CI, see issue #2004",
-        raises=subprocess.CalledProcessError,
-    )
     @with_rw_directory
     def test_installation(self, rw_dir):
         venv = self._set_up_venv(rw_dir)