refs and cleanup

Author: SimonCropp

src/Directory.Packages.props

@@ -7,7 +7,7 @@
     <PackageVersion Include="ProjectDefaults" Version="1.0.172" />
     <PackageVersion Include="Verify.TUnit" Version="31.13.2" />
     <PackageVersion Include="Argon" Version="0.33.5" />
-    <PackageVersion Include="DiffEngine" Version="18.4.2" />
+    <PackageVersion Include="DiffEngine" Version="19.0.0" />
     <PackageVersion Include="EmptyFiles" Version="8.17.2" />
     <PackageVersion Include="SimpleInfoName" Version="3.2.0" />
     <PackageVersion Include="Verify" Version="31.13.2" />