Bump Polyfill from 6.2.3 to 6.8.0 (#320)

Bumps [Polyfill](https://github.com/SimonCropp/Polyfill) from 6.2.3 to 6.8.0.
- [Commits](SimonCropp/Polyfill@6.2.3...6.8.0)

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

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

src/Directory.Build.props

@@ -42,7 +42,7 @@
 
   <ItemGroup>
     <PackageReference Include="ConfigureAwaitChecker.Analyzer" Version="5.0.0.1" PrivateAssets="All" />
-    <PackageReference Include="Polyfill " Version="6.2.3" PrivateAssets="All" />
+    <PackageReference Include="Polyfill " Version="6.8.0" PrivateAssets="All" />
   </ItemGroup>
 
 </Project>