Exclude packages.lock.json from editorconfig checks

The packages.lock.json files are auto-generated by .NET and don't
include a final newline, causing the editorconfig checker to fail.
Since we can't control the format of these generated files, we
exclude them from the checks.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: paulirwin

.editorconfig-checker.json

@@ -8,7 +8,8 @@
     "\\.resx$",
     "\\.DotSettings$",
     "App\\.config$",
-    "\\.htaccess$"
+    "\\.htaccess$",
+    "packages\\.lock\\.json$"
   ],
   "AllowedContentTypes": [],
   "PassedFiles": [],