Update the GH squash commit RegEx to remove the PR number.

[JoeRobich]

Noticed that we were not removing PR numbers when fixing up the C# ext. CHANGELOG. Leaving the PR number in allows GH to turn it into a link when the number is in the range to be valid.

BEFORE:

• React to NuGet package pruning warnings (#11496) (PR: #11496)
• Add a couple of "stress tests" to the integration test project (#11481) (PR: #11481)
• Fix a couple of options in the old options screen (#11486) (PR: #11486)
• Don't use Directory.Exists to check if a path is relative (#11483) (PR: #11483)
• Fix another IDE0040 violation (#11474) (PR: #11474)
• Remove accessibility modifiers from interface members (#11472) (PR: #11472)

AFTER:

• React to NuGet package pruning warnings (PR: #11496)
• Add a couple of "stress tests" to the integration test project (PR: #11481)
• Fix a couple of options in the old options screen (PR: #11486)
• Don't use Directory.Exists to check if a path is relative (PR: #11483)
• Fix another IDE0040 violation (PR: #11474)
• Remove accessibility modifiers from interface members (PR: #11472)