deps: pin JsonPatch.Net to version <=4.0.1 (#1032)

Pinned Json.Patch to version 4.0.1 to remain on the last free release
before the maintainer enforces a paid maintenance fee (starting 1 Feb
2026) via a new EULA on binary releases/NuGet packages. This prevents
our builds from inheriting the upcoming licensing change while keeping
functionality unchanged.

Author: kimpenhaus

renovate.json

@@ -46,6 +46,10 @@
     {
       "matchFileNames": ["docs/**/*"],
       "semanticCommitScope": "docs"
+    },
+    {
+      "matchPackageNames": ["JsonPatch.Net"],
+      "allowedVersions": "<=4.0.1"
     }
   ]
-}
+}