Allow portalocker version 3

See https://github.com/wolph/portalocker/releases/tag/v3.0.0;
portalocker 3 drops support for end-of-life Python versions older than
3.9. The older portalocker versions allowed in the range still cover
these Python interpreter versions.

setup.py

@@ -20,7 +20,7 @@
     python_requires=">=3.7",
     install_requires=[
         'msal>=1.29,<2',  # Use TokenCache.search() from MSAL Python 1.29+
-        'portalocker<3,>=1.4',
+        'portalocker<4,>=1.4',
 
         ## We choose to NOT define a hard dependency on this.
         # "pygobject>=3,<4;platform_system=='Linux'",