Pin PyGObject to 3.50.0 (#233)

Newer versions of PyGObject depend on libgirepository-2.0-dev which isn't packaged for Debian. This leads to build failures like

 Collecting PyGObject
 Downloading pygobject-3.52.1.tar.gz (1.2 MB)
 ...

 × Preparing metadata (pyproject.toml) did not run successfully.
 │ exit code: 1
 ╰─> [24 lines of output]
 ...

 ../meson.build:31:9: ERROR: Dependency 'girepository-2.0' is required but not found.

Pin the version of PyGObject to 3.50.0 which is the latest version known to work.

Fixes sonic-net/sonic-buildimage#21984

This needs to be cherry-picked onto the 202411branch. Probably 202405 and 202311 too. I don't think it'll apply cleanly to 202305 so that'd need a branch specific change.

Author: mssonicbld

setup.py

@@ -47,7 +47,7 @@
         'dbus-python',
         'systemd-python',
         'Jinja2>=2.10',
-        'PyGObject',
+        'PyGObject==3.50.0',
         'pycairo==1.26.1',
         'psutil'
     ] + sonic_dependencies,