Test Python 3.12 in Cygwin on CI

As well as Python 3.9 as before.

Author: EliahKagan

.github/workflows/cygwin-test.yml

@@ -7,6 +7,14 @@ jobs:
     runs-on: windows-latest
 
     strategy:
+      matrix:
+        python-version: ["3.9", "3.12"]
+        include:
+        - python-version: "3.9"
+          package-suffix: "39"
+        - python-version: "3.12"
+          package-suffix: "312"
+
       fail-fast: false
 
     env:
@@ -30,7 +38,12 @@ jobs:
     - name: Install Cygwin
       uses: cygwin/cygwin-install-action@v5
       with:
-        packages: python39 python39-pip python39-virtualenv git wget
+        packages: >
+          python${{ matrix.package-suffix }}
+          python${{ matrix.package-suffix }}-pip
+          python${{ matrix.package-suffix }}-virtualenv
+          git
+          wget
         add-to-path: false  # No need to change $PATH outside the Cygwin environment.
 
     - name: Arrange for verbose output
@@ -58,7 +71,7 @@ jobs:
 
     - name: Set up virtualenv
       run: |
-        python3.9 -m venv --without-pip .venv
+        python${{ matrix.python-version }} -m venv --without-pip .venv
         echo 'BASH_ENV=.venv/bin/activate' >>"$GITHUB_ENV"
 
     - name: Bootstrap pip in virtualenv