build!: update library to use Node 12 (#589)

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md
Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: alexander-fenster

dataproc/package.json

@@ -6,7 +6,7 @@
     "*.js"
   ],
   "engines": {
-    "node": ">=10"
+    "node": ">=12.0.0"
   },
   "repository": "googleapis/nodejs-dataproc",
   "private": true,