plugin-api: tweak @types dependencies

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

packages/plugin-api/package.json

@@ -32,7 +32,6 @@
     "@backstage/config": "^0.1.3",
     "@backstage/theme": "^0.2.3",
     "@types/react": "^16.9",
-    "@types/prop-types": "^15.7.3",
     "history": "^5.0.0",
     "prop-types": "^15.7.2",
     "react": "^16.12.0",
@@ -50,6 +49,7 @@
     "@testing-library/user-event": "^13.1.8",
     "@types/jest": "^26.0.7",
     "@types/node": "^14.14.32",
+    "@types/prop-types": "^15.7.3",
     "@types/zen-observable": "^0.8.0",
     "cross-fetch": "^3.0.6",
     "msw": "^0.21.3"