Update the Node.js version

.appveyor.yml

@@ -4,14 +4,15 @@ build: off
 platform: x64
 environment:
   matrix:
+    - nodejs_version: 12
+    - nodejs_version: 11
     - nodejs_version: 10
-    - nodejs_version: 8
 install:
   - ps: Install-Product node $env:nodejs_version x64
   - set CI=true
   - npm i -g npm@latest
   - set PATH=%APPDATA%\npm;%PATH%
-  - npm install
+  - npm i
 matrix:
   fast_finish: true
 shallow_clone: true

.travis.yml

@@ -1,7 +1,8 @@
 language: node_js
 node_js:
+  - 12
+  - 11
   - 10
-  - 8
 before_install:
   - npm i -g npm@latest
 cache:

package.json

@@ -66,7 +66,7 @@
 		"sass-lint": "^1.12.1"
 	},
 	"engines": {
-		"node": ">=4"
+		"node": ">=10.0.0"
 	},
 	"scripts": {
 		"start": "run-p build watch serve",