chore: bump version to 2.11.3 and update documentation

- Bump version from 2.11.2 to 2.11.3
- Update README.md version badge
- Add CHANGELOG.md entry documenting the fix for n8n_update_partial_workflow tool
- Fix resolves GitHub issues #159 and #168

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "n8n-mcp",
-  "version": "2.11.2",
+  "version": "2.11.3",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "n8n-mcp",
-      "version": "2.11.2",
+      "version": "2.11.3",
       "license": "MIT",
       "dependencies": {
         "@modelcontextprotocol/sdk": "^1.13.2",