chore: add back node v6 support

No change to logic. This adds back node v6 support to partially revert
#186. I'm hoping that v6 support is
easier now that we rely on GitHub actions for codecov. The motivation
for this change is so that we can make 0.3.x patch releases if
necessary.

Author: nfischer

.github/workflows/main.yml

@@ -10,6 +10,8 @@ jobs:
       fail-fast: false
       matrix:
         node-version:
+          - 6
+          - 7
           - 8
           - 9
           - 10

README.md

@@ -9,7 +9,7 @@
 commands, providing an easy solution for simple Unix-like, cross-platform
 commands in npm package scripts.
 
-`shx` is proudly tested on every node release since <!-- start minVersion -->`v8`<!-- stop minVersion -->!
+`shx` is proudly tested on every node release since <!-- start minVersion -->`v6`<!-- stop minVersion -->!
 
 ## Difference Between ShellJS and shx
 

package.json

@@ -75,6 +75,6 @@
     "shelljs": "^0.8.5"
   },
   "engines": {
-    "node": ">=8"
+    "node": ">=6"
   }
 }

scripts/check-node-support.js

@@ -8,7 +8,7 @@ var yaml = require('js-yaml');
 var shell = require('shelljs');
 
 // This is the authoritative list of supported node versions.
-var MIN_NODE_VERSION = 8;
+var MIN_NODE_VERSION = 6;
 var MAX_NODE_VERSION = 14;
 
 function checkReadme(minNodeVersion) {