chore: switch to use Node 12 (#3400)

.nvmrc

@@ -1 +1 @@
-10
+12

.travis.yml

@@ -1,10 +1,10 @@
 language: node_js
+
 node_js:
-  - "8"
+  - "12"
+
 notifications:
   email: false
-before_install:
-# package-lock.json was introduced in npm@5
-  - '[[ $(node -v) =~ ^v9.*$ ]] || npm install -g npm@latest' # skipped when using node 9
+
 script:
   - npm test # && npm run integration

package.json

@@ -109,7 +109,7 @@
     "walk-sync": "^2.0.2"
   },
   "engines": {
-    "node": "10"
+    "node": ">= 12"
   },
   "standard": {
     "ignore": [