chore(deps): downgrade moq to 4.18.4 (#327)

Author: JamieMagee

test/Directory.Build.props

@@ -9,7 +9,7 @@
     </PackageReference>
     <PackageReference Include="FluentAssertions" Version="6.11.0"/>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.7.0"/>
-    <PackageReference Include="Moq" Version="4.20.1"/>
+    <PackageReference Include="Moq" Version="4.18.4"/>
     <PackageReference Include="xunit" Version="2.5.0"/>
     <PackageReference Include="xunit.runner.visualstudio" PrivateAssets="all" Version="2.5.0">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>