Bump to Node v12

This is the LTS version now, might as well use it.

package-lock.json

@@ -536,9 +536,9 @@
       }
     },
     "@types/node": {
-      "version": "11.13.22",
-      "resolved": "https://registry.npmjs.org/@types/node/-/node-11.13.22.tgz",
-      "integrity": "sha512-rOsaPRUGTOXbRBOKToy4cgZXY4Y+QSVhxcLwdEveozbk7yuudhWMpxxcaXqYizLMP3VY7OcWCFtx9lGFh5j5kg==",
+      "version": "12.11.7",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-12.11.7.tgz",
+      "integrity": "sha512-JNbGaHFCLwgHn/iCckiGSOZ1XYHsKFwREtzPwSGCVld1SGhOlmZw2D4ZI94HQCrBHbADzW9m4LER/8olJTRGHA==",
       "dev": true
     },
     "@types/range-parser": {

package.json

@@ -26,7 +26,7 @@
     "@types/express": "^4.16.1",
     "@types/jest": "^24.0.11",
     "@types/multiparty": "^0.0.32",
-    "@types/node": "^11.11.3",
+    "@types/node": "^12.11.7",
     "jest": "^24.5.0",
     "jest-haste-map": "^24.5.0",
     "jest-resolve": "^24.5.0",
@@ -48,5 +48,8 @@
   },
   "prettier": {
     "trailingComma": "es5"
+  },
+  "engines": {
+    "node": ">=12"
   }
 }