Bump Polyfill from 4.9.0 to 5.0.0 in /src

Bumps [Polyfill](https://github.com/SimonCropp/Polyfill) from 4.9.0 to 5.0.0.
- [Commits](SimonCropp/Polyfill@4.9.0...5.0.0)

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

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

src/AustralianProtectiveMarkings/AustralianProtectiveMarkings.csproj

@@ -6,7 +6,7 @@
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="System.Collections.Immutable" Version="8.0.0" Condition="'$(TargetFramework)' != 'net8.0'" />
-    <PackageReference Include="Polyfill" Version="4.9.0" PrivateAssets="all" />
+    <PackageReference Include="Polyfill" Version="5.0.0" PrivateAssets="all" />
     <PackageReference Include="ProjectDefaults" Version="1.0.126" PrivateAssets="all" />
     <PackageReference Include="System.IO.Compression" Version="4.3.0" Condition="$(TargetFramework) == net48" />
   </ItemGroup>

src/Verify.AustralianProtectiveMarkings/Verify.AustralianProtectiveMarkings.csproj

@@ -8,7 +8,7 @@
     <PackageReference Include="NodaTime" Version="3.1.11" />
     <PackageReference Include="Verify" Version="24.1.0" />
     <PackageReference Include="ProjectDefaults" Version="1.0.126" PrivateAssets="all" />
-    <PackageReference Include="Polyfill" Version="4.9.0" PrivateAssets="all" />
+    <PackageReference Include="Polyfill" Version="5.0.0" PrivateAssets="all" />
     <ProjectReference Include="..\AustralianProtectiveMarkings\AustralianProtectiveMarkings.csproj" />
   </ItemGroup>
 </Project>