return to supporting node >= 8

downgraded xo and mocha. bin-wrapper still supports >= 6, which is really all that matters.

.github/workflows/test.yml

@@ -11,7 +11,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest, macOS-latest]
-        node: [14.x, 13.x, 12.x, 10.x]
+        node: [14.x, 12.x, 10.x, 8.x]
       fail-fast: false
     runs-on: ${{ matrix.os }}
     name: Node ${{ matrix.node }} on ${{ matrix.os }}

package.json

@@ -30,15 +30,15 @@
   },
   "devDependencies": {
     "bin-check": "^4.1.0",
-    "mocha": "*",
-    "xo": "*"
+    "mocha": "~6.x",
+    "xo": "~0.25.x"
   },
   "scripts": {
     "postinstall": "node lib/install.js",
     "test": "xo && mocha && node cli.js env"
   },
   "engines": {
-    "node": ">=10"
+    "node": ">=8"
   },
   "files": [
     "lib/*.js",