fix(deps): update dependency proj4 to v2.21.0

Author: renovate[bot]

package.json

@@ -64,7 +64,7 @@
     "ol": "^10.8.0",
     "ol-contextmenu": "^5.5.0",
     "ol-mapbox-style": "^13.4.0",
-    "proj4": "2.15.0",
+    "proj4": "2.21.0",
     "sortablejs": "1.15.3",
     "typescript": "^5.3.3",
     "whatwg-fetch": "3.6.20",