chore: drop Node.js < 10 support

BREAKING CHANGE: drop Node.js < 10 support

Author: dbstratta

.travis.yml

@@ -25,8 +25,6 @@ jobs:
       node_js:
         - '11'
         - '10'
-        - '9'
-        - '8'
       script:
         - yarn test:ci
         - yarn coverage

README.md

@@ -362,7 +362,7 @@ Yes! You can have as many env objects as you want!
 
 ## Node.js support
 
-Node.js version 8 or higher.
+Node.js version 10 or higher.
 
 ## Maintainers
 

appveyor.yml

@@ -1,8 +1,7 @@
 environment:
   matrix:
-    - nodejs_version: '8'
-    - nodejs_version: '9'
     - nodejs_version: '10'
+    - nodejs_version: '11'
 
 install:
   - ps: Install-Product node $env:nodejs_version