Update Moq

Also removes the duplicate PackageReference

tests/ImageSharp.Tests/ImageSharp.Tests.csproj

@@ -32,11 +32,10 @@
     <PackageReference Include="xunit" Version="2.3.1" />
     <PackageReference Include="xunit.runner.console" Version="2.3.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.3.1" />
-    <PackageReference Include="Moq" Version="4.7.145" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.7.0" />
     <PackageReference Include="xunit" Version="2.3.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.3.1" />
-    <PackageReference Include="Moq" Version="4.8.1" />
+    <PackageReference Include="Moq" Version="4.8.2" />
   </ItemGroup>
   <ItemGroup>
     <AdditionalFiles Include="..\..\stylecop.json" />