Bump Polyfill from 8.8.0 to 9.3.1

---
updated-dependencies:
- dependency-name: Polyfill
  dependency-version: 9.3.1
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

IconHelper/IconHelper.csproj

@@ -12,6 +12,7 @@
     <PackageReference Include="CommandLineParser" />
     <PackageReference Include="ktsu.CaseConverter" />
     <PackageReference Include="ktsu.Extensions" />
+  <PackageReference Include="Polyfill" VersionOverride="9.3.1" />
     <PackageReference Include="SixLabors.ImageSharp" />
   </ItemGroup>
 </Project>