Bump Verify.DiffPlex from 3.1.1 to 3.1.2 in /src (#596)

Author: dependabot[bot]

src/Directory.Packages.props

@@ -11,7 +11,7 @@
     <PackageVersion Include="ProjectDefaults" Version="1.0.139" />
     <PackageVersion Include="SixLabors.ImageSharp" Version="3.1.5" />
     <PackageVersion Include="Verify" Version="27.0.0" />
-    <PackageVersion Include="Verify.DiffPlex" Version="3.1.1" />
+    <PackageVersion Include="Verify.DiffPlex" Version="3.1.2" />
     <PackageVersion Include="Verify.Nunit" Version="27.0.0" />
   </ItemGroup>
 </Project>