chore: drop support for Node.js < 8.10 to align with react-docgen@5

BREAKING CHANGE: Node.js v8.10 or newer is required.

Author: ZauberNerd

.tav.yml

@@ -1,17 +1,5 @@
-node-4-5:
-  name: react-docgen
-  node: '>= 4.0.0 < 6.0.0'
-  versions: '>= 2.17.0 < 3.0.0'
-  commands: npm run test:unit
-
-node-6-7:
-  name: react-docgen
-  node: '>= 6.0.0 < 8.0.0'
-  versions: '>= 3.0.0 < 5.0.0 || >= 3.0.0-beta1 <= 3.0.0-beta12 || >= 3.0.0-rc.0 <= 3.0.0-rc.2'
-  commands: npm run test:unit
-
 node-8-x:
   name: react-docgen
-  node: '>= 8.0.0'
-  versions: '>= 3.0.0 < 5.0.0 || 5.0.0-beta.1'
+  node: '>= 8.10.0'
+  versions: '>= 3.0.0 <= 6.0.0 || 5.0.0-beta.1'
   commands: npm run test:unit

.travis.yml

@@ -1,9 +1,7 @@
 language: node_js
 
 node_js:
-  - 4
-  - 6
-  - 8
+  - '8.10.0'
   - 10
   - 12
 

package.json

@@ -18,7 +18,7 @@
     "url": "https://github.com/nerdlabs/react-docgen-displayname-handler.git"
   },
   "engines": {
-    "node": ">=4"
+    "node": ">=8.10.0"
   },
   "files": [
     "distribution"
@@ -51,7 +51,7 @@
         "env",
         {
           "targets": {
-            "node": "4"
+            "node": "8.10.0"
           }
         }
       ]