Bump Polyfill from 8.8.0 to 9.6.0

---
updated-dependencies:
- dependency-name: Polyfill
  dependency-version: 9.6.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

AppDataStorage/AppDataStorage.csproj

@@ -8,6 +8,7 @@
     <PackageReference Include="ktsu.CaseConverter" />
     <PackageReference Include="ktsu.RoundTripStringJsonConverter" />
     <PackageReference Include="ktsu.Semantics.Paths" />
+  <PackageReference Include="Polyfill" />
     <PackageReference Include="TestableIO.System.IO.Abstractions" />
     <PackageReference Include="TestableIO.System.IO.Abstractions.Wrappers" />
   </ItemGroup>

Directory.Packages.props

@@ -11,6 +11,7 @@
     <PackageVersion Include="Microsoft.Testing.Extensions.CodeCoverage" Version="18.3.1" />
     <PackageVersion Include="MSTest.TestAdapter" Version="4.0.2" />
     <PackageVersion Include="MSTest.TestFramework" Version="4.0.2" />
+    <PackageVersion Include="Polyfill" Version="9.6.0" />
     <PackageVersion Include="TestableIO.System.IO.Abstractions" Version="22.0.15" />
     <PackageVersion Include="TestableIO.System.IO.Abstractions.TestingHelpers" Version="22.1.0" />
     <PackageVersion Include="TestableIO.System.IO.Abstractions.Wrappers" Version="22.0.15" />