bug: remove mgt-spfx dependency from react webpart sample (#2196)

Author: gavinbarron

samples/sp-webpart/package.json

@@ -13,7 +13,6 @@
   "dependencies": {
     "@microsoft/mgt-element": "*",
     "@microsoft/mgt-react": "*",
-    "@microsoft/mgt-spfx": "*",
     "@microsoft/mgt-spfx-utils": "*",
     "@microsoft/mgt-sharepoint-provider": "*",
     "@microsoft/sp-core-library": "1.16.1",