Update all deps and require Node.js >= 6.

Author: XhmikosR

.travis.yml

@@ -3,9 +3,9 @@ sudo: false
 language: node_js
 
 node_js:
-  - "4"
   - "6"
-  - "7"
+  - "8"
+  - "10"
 
 matrix:
   fast_finish: true

CONTRIBUTING.md

@@ -1 +1 @@
-Please see the [Contributing to grunt](http://gruntjs.com/contributing) guide for information on contributing to this project.
+Please see the [Contributing to grunt](https://gruntjs.com/contributing) guide for information on contributing to this project.

Gruntfile.js

@@ -86,7 +86,6 @@ module.exports = function (grunt) {
 
   grunt.registerTask('default', [
     'test',
-    'contrib-core',
-    'contrib-ci:skipIfExists'
+    'build-contrib'
   ]);
 };

README.md

@@ -6,7 +6,7 @@
 
 ## Getting Started
 
-If you haven't used [Grunt](http://gruntjs.com/) before, be sure to check out the [Getting Started](http://gruntjs.com/getting-started) guide, as it explains how to create a [Gruntfile](http://gruntjs.com/sample-gruntfile) as well as install and use Grunt plugins. Once you're familiar with that process, you may install this plugin with this command:
+If you haven't used [Grunt](https://gruntjs.com/) before, be sure to check out the [Getting Started](https://gruntjs.com/getting-started) guide, as it explains how to create a [Gruntfile](https://gruntjs.com/sample-gruntfile) as well as install and use Grunt plugins. Once you're familiar with that process, you may install this plugin with this command:
 
 ```shell
 npm install grunt-contrib-cssmin --save-dev
@@ -121,4 +121,4 @@ cssmin: {
 
 Task submitted by [Tim Branyen](http://tbranyen.com/)
 
-*This file was generated on Thu Jul 27 2017 11:31:20.*
+*This file was generated on Fri Sep 07 2018 02:49:39.*

appveyor.yml

@@ -5,13 +5,11 @@ version: "{build}"
 # What combinations to test
 environment:
   matrix:
-    - nodejs_version: "4"
-      platform: x64
-    - nodejs_version: "4"
-      platform: x86
     - nodejs_version: "6"
       platform: x86
-    - nodejs_version: "7"
+    - nodejs_version: "8"
+      platform: x86
+    - nodejs_version: "10"
       platform: x86
 
 install:

package-lock.json

@@ -4,28 +4,28 @@
   "version": "2.2.1",
   "author": {
     "name": "Grunt Team",
-    "url": "http://gruntjs.com/"
+    "url": "https://gruntjs.com/"
   },
   "repository": "gruntjs/grunt-contrib-cssmin",
   "license": "MIT",
   "engines": {
-    "node": ">=4.0"
+    "node": ">=6.0"
   },
   "main": "tasks/cssmin.js",
   "scripts": {
     "test": "grunt test"
   },
   "dependencies": {
-    "chalk": "^1.0.0",
-    "clean-css": "~4.1.1",
+    "chalk": "^2.4.1",
+    "clean-css": "~4.2.1",
     "maxmin": "^2.1.0"
   },
   "devDependencies": {
-    "grunt": "^1.0.0",
-    "grunt-contrib-clean": "^1.0.0",
-    "grunt-contrib-internal": "^1.1.0",
-    "grunt-contrib-jshint": "^1.0.0",
-    "grunt-contrib-nodeunit": "^1.0.0"
+    "grunt": "^1.0.3",
+    "grunt-contrib-clean": "^1.1.0",
+    "grunt-contrib-internal": "^3.1.0",
+    "grunt-contrib-jshint": "^1.1.0",
+    "grunt-contrib-nodeunit": "^2.0.0"
   },
   "keywords": [
     "gruntplugin",