Bump Polyfill from 1.30.0 to 1.31.0 in /src

Bumps [Polyfill](https://github.com/SimonCropp/Polyfill) from 1.30.0 to 1.31.0.
- [Commits](SimonCropp/Polyfill@1.30.0...1.31.0)

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

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

src/Verify.DiffPlex/Verify.DiffPlex.csproj

@@ -5,7 +5,7 @@
   <ItemGroup>
     <PackageReference Include="Argon" Version="0.13.0" />
     <PackageReference Include="DiffPlex" Version="1.7.1" />
-    <PackageReference Include="Polyfill" Version="1.30.0" PrivateAssets="all" />
+    <PackageReference Include="Polyfill" Version="1.31.0" PrivateAssets="all" />
     <PackageReference Include="Verify" Version="22.1.4" />
     <PackageReference Include="ProjectDefaults" Version="1.0.101" PrivateAssets="all" />
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.1.1" PrivateAssets="All" Condition="$(Configuration) == 'Release'" />