chore(deps): update dependency diffengine to 15.9.0 (#722)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

src/Meziantou.Framework.InlineSnapshotTesting/Meziantou.Framework.InlineSnapshotTesting.csproj

@@ -27,7 +27,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="DiffEngine" Version="15.8.0" />
+    <PackageReference Include="DiffEngine" Version="15.9.0" />
     <PackageReference Include="JsonPath.Net" Version="2.1.0" />
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.12.0" />
   </ItemGroup>