bug(layers): Add missing @types/geojson dependency (#10268)

`geojson` types are imported in the following places:
* https://github.com/visgl/deck.gl/blob/e089fb55b91f4c39779b39d256ac957bf68f8a08/modules/layers/src/geojson-layer/geojson.ts#L16
* https://github.com/visgl/deck.gl/blob/e089fb55b91f4c39779b39d256ac957bf68f8a08/modules/layers/src/geojson-layer/geojson-layer.ts#L21

But `@types/geojson` is not declared as a dependency

Co-authored-by: Chris Gervang <chrisgervang@users.noreply.github.com>

Author: MixMasterMitch

modules/layers/package.json

@@ -44,6 +44,7 @@
     "@math.gl/core": "^4.1.0",
     "@math.gl/polygon": "^4.1.0",
     "@math.gl/web-mercator": "^4.1.0",
+    "@types/geojson": "^7946.0.16",
     "earcut": "^2.2.4"
   },
   "peerDependencies": {