[CI/CD] Fix Pillow packaging build errors

Pillow have dropped 32-bit wheels from v10 onwards so force install of
older v9 wheels since we don't want to build from src.

Refs: https://github.com/python-pillow/Pillow/issues/6941#issuecomment-1604058002

.github/workflows/cd.yml

@@ -62,8 +62,11 @@ jobs:
           python -m pip install --no-index --find-links="C:\GTK\release\python" pycairo PyGObject
 
       - name: Install Python dependencies
+        # Pillow no longer provides 32-bit wheels for Windows
+        # so specify only-binary to install old version.
         run: >
           python -m pip install
+          --only-binary=pillow
           twisted[tls]==22.4.0
           libtorrent==${{ matrix.libtorrent }}
           pyinstaller==4.10