Bump Polyfill from 9.13.0 to 9.15.0

---
updated-dependencies:
- dependency-name: Polyfill
  dependency-version: 9.15.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

src/Directory.Packages.props

@@ -7,7 +7,7 @@
     <PackageVersion Include="Bogus" Version="35.6.5" />
     <PackageVersion Include="MarkdownSnippets.MsBuild" Version="28.0.0" />
     <PackageVersion Include="Microsoft.Sbom.Targets" Version="4.1.5" />
-    <PackageVersion Include="Polyfill" Version="9.13.0" />
+    <PackageVersion Include="Polyfill" Version="9.15.0" />
     <PackageVersion Include="ProjectDefaults" Version="1.0.172" />
     <PackageVersion Include="System.CodeDom" Version="10.0.3" />
     <PackageVersion Include="UnicodeInformation" Version="2.7.1" />