Bump Polyfill from 7.19.0 to 7.20.0 in /src

Bumps [Polyfill](https://github.com/SimonCropp/Polyfill) from 7.19.0 to 7.20.0.
- [Commits](SimonCropp/Polyfill@7.19.0...7.20.0)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

src/Directory.Packages.props

@@ -6,7 +6,7 @@
   <ItemGroup>
     <PackageVersion Include="MarkdownSnippets.MsBuild" Version="27.0.2" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.13.0" />
-    <PackageVersion Include="Polyfill" Version="7.19.0" />
+    <PackageVersion Include="Polyfill" Version="7.20.0" />
     <PackageVersion Include="ProjectDefaults" Version="1.0.147" />
     <PackageVersion Include="Verify" Version="28.13.0" />
     <PackageVersion Include="Verify.DiffPlex" Version="3.1.2" />