pg-query-stream: Add missing peer dependency on pg (brianc#2813)

pg-query-stream depends on pg-cursor, which has a peer dependency on pg.

Author: matthieusieben

packages/pg-query-stream/package.json

@@ -42,6 +42,9 @@
     "ts-node": "^8.5.4",
     "typescript": "^4.0.3"
   },
+  "peerDependencies": {
+    "pg": "^8"
+  },
   "dependencies": {
     "pg-cursor": "^2.7.4"
   }