Fix Build workflow

[christianhelle]

This pull request includes several changes across different files to update the build environment, remove a package reference, and improve code robustness. The most important changes include switching the build environment to Windows, removing a specific package reference, and adding null-forgiving operators to avoid potential null reference issues.

Build environment update:

• .github/workflows/build.yml: Changed the build environment to run on windows-latest instead of ubuntu-latest and added a step to set up .NET 9.0.

Package reference removal:

• src/Refitter.SourceGenerator/Refitter.SourceGenerator.csproj: Removed the Microsoft.CodeAnalysis.CSharp package reference.

Code robustness improvements:

• src/Refitter.Tests/SerializerTests.cs: Added null-forgiving operators to CodeGeneratorSettings.PropertyNameGenerator in the Can_Deserialize_RefitGeneratorSettingsWithoutNameGenerators and Deserialize_Is_Case_Insensitive methods to prevent potential null reference exceptions. [1] [2]

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.93%. Comparing base (91a5544) to head (44a6a23).
Report is 13 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #567   +/-   ##
=======================================
  Coverage   98.93%   98.93%           
=======================================
  Files          53       53           
  Lines        2541     2541           
=======================================
  Hits         2514     2514           
  Misses          4        4           
  Partials       23       23           

Flag	Coverage Δ
unittests	98.93% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.