Bump NuGet packages

[martincostello]

Update NuGet packages that dependabot is failing to update.

[Copilot]

Pull Request Overview

This PR updates several NuGet package versions to their latest available releases, addressing packages that dependabot was unable to update automatically.

• Microsoft.Extensions packages updated from 9.7.0 to 9.8.0
• ReportGenerator updated from 5.4.8 to 5.4.12
• SonarAnalyzer.CSharp updated from 10.12.0 to 10.15.0
• System.Text.Json updated from 9.0.7 to 9.0.8

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.12%. Comparing base (d285b23) to head (eecc435).
⚠️ Report is 3 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2738   +/-   ##
=======================================
  Coverage   96.12%   96.12%           
=======================================
  Files         309      309           
  Lines        7118     7118           
  Branches     1008     1008           
=======================================
  Hits         6842     6842           
  Misses        222      222           
  Partials       54       54           

Flag	Coverage Δ
linux	96.12% <ø> (+0.26%)	⬆️
macos	96.12% <ø> (ø)
windows	96.11% <ø> (ø)

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