Merge pull request #95 from Doraku/dependabot/nuget/source/Polyfill-9.18.0

Bump Polyfill from 9.13.0 to 9.18.0

Author: Doraku

source/Directory.Build.props

@@ -22,7 +22,7 @@
 	</PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Polyfill" Version="9.13.0" PrivateAssets="all" />
+    <PackageReference Include="Polyfill" Version="9.18.0" PrivateAssets="all" />
   </ItemGroup>
 
   <Import Project="$(MSBuildThisFileDirectory)DefaultCSharp\projects\DefaultCSharp.props" />