update ruby versions (#88)

Author: nijikon

.gitignore

@@ -1,3 +1,4 @@
+.bundle
 coverage
 vendor/bundle
 .coditsu/local.yml

.ruby-version

@@ -1 +1 @@
-2.7.1
+2.7.2

.travis.yml

@@ -17,17 +17,17 @@ test: &test
 jobs:
   include:
     - <<: *test
-      rvm: 2.7.0
+      rvm: 2.7.2
     - <<: *test
-      rvm: 2.6.5
+      rvm: 2.6.6
     - <<: *test
-      rvm: 2.5.7
+      rvm: 2.5.8
     - <<: *test
       rvm: jruby-9.2.9.0
 
     - stage: coditsu
       language: ruby
-      rvm: 2.7.0
+      rvm: 2.7.2
       before_install:
         - yes | gem update --system
       script: \curl -sSL https://api.coditsu.io/run/ci | bash