fix(hidi): remove Humanizer.Inflections namespace for Humanizer 3.x compatibility

Co-authored-by: baywet <7905502+baywet@users.noreply.github.com>

Author: Copilot

src/Microsoft.OpenApi.Hidi/Formatters/PowerShellFormatter.cs

@@ -5,7 +5,6 @@
 using System.Text;
 using System.Text.RegularExpressions;
 using Humanizer;
-using Humanizer.Inflections;
 using Microsoft.OpenApi.Hidi.Extensions;
 
 namespace Microsoft.OpenApi.Hidi.Formatters