chore(deps): update dependency polyfill to 9.21.0 (#1142)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

Directory.Packages.props

@@ -23,7 +23,7 @@
     <PackageVersion Include="NUnit" Version="4.5.1" />
     <PackageVersion Include="NUnit3TestAdapter" Version="6.1.0" />
     <PackageVersion Include="NUnit.Analyzers" Version="4.12.0" />
-    <PackageVersion Include="Polyfill" Version="9.20.0" />
+    <PackageVersion Include="Polyfill" Version="9.21.0" />
     <PackageVersion Include="PublicApiGenerator" Version="11.5.4" />
     <PackageVersion Include="TUnit" Version="1.19.57" />
     <PackageVersion Include="TUnit.Core" Version="1.19.57" />