.travis.yml in asynchronic-1.5.2 vs .travis.yml in asynchronic-1.6.0

@@ -6,10 +6,11 @@
   - 2.1
   - 2.2
   - 2.3.0
   - 2.4.0
   - 2.5.0
+  - 2.6.0
   - jruby-1.7.25
   - jruby-9.1.7.0
   - ruby-head
   - jruby-head
 
@@ -18,9 +19,10 @@
   allow_failures:
     - rvm: ruby-head
     - rvm: jruby-head
 
 before_install:
-  - gem install bundler
+  - rvm all-gemsets do gem uninstall bundler -ax || true
+  - gem install bundler -v "< 2"
 
 services:
   - redis-server
\ No newline at end of file