Update ruby versions on CI

Author: byroot

.travis.yml

@@ -9,9 +9,11 @@ before_install:
 script: make
 
 rvm:
-  - 2.3.8
-  - 2.4.5
-  - 2.5.3
+  - "2.3"
+  - "2.4"
+  - "2.5"
+  - "2.6"
+  - "2.7"
   - jruby-9.1.17.0
 
 sudo: false
@@ -29,23 +31,17 @@ env:
     - DRIVER=hiredis   REDIS_BRANCH=5.0
     - DRIVER=synchrony REDIS_BRANCH=5.0
 
-branches:
-  only:
-    - staging
-    - trying
-    - master
-
 matrix:
   exclude:
     - rvm: jruby-9.1.17.0
   include:
     - rvm: jruby-9.1.17.0
       env: DRIVER=ruby REDIS_BRANCH=5.0 LOW_TIMEOUT=0.3
-    - rvm: 2.3.8
+    - rvm: "2.3"
       env: DRIVER=ruby REDIS_BRANCH=3.0
-    - rvm: 2.3.8
+    - rvm: "2.3"
       env: DRIVER=ruby REDIS_BRANCH=3.2
-    - rvm: 2.3.8
+    - rvm: "2.3"
       env: DRIVER=ruby REDIS_BRANCH=4.0
 
 notifications: