.travis.yml: s/next/4/

jsx-eslint#1843 (comment)

Author: papandreou

.travis.yml

@@ -32,13 +32,13 @@ matrix:
     - node_js: '6'
       env: TEST=true ESLINT=5
     - node_js: '9'
-      env: TEST=true ESLINT=next
+      env: TEST=true ESLINT=4
     - node_js: '8'
-      env: TEST=true ESLINT=next
+      env: TEST=true ESLINT=4
     - node_js: '7'
-      env: TEST=true ESLINT=next
+      env: TEST=true ESLINT=4
     - node_js: '6'
-      env: TEST=true ESLINT=next
+      env: TEST=true ESLINT=4
     - node_js: '9'
       env: TEST=true ESLINT=3
     - node_js: '8'
@@ -55,4 +55,4 @@ matrix:
     - node_js: '9'
     - node_js: '7'
     - node_js: '5'
-    - env: TEST=true ESLINT=next
+    - env: TEST=true ESLINT=4