.travis.yml in stackprof-0.2.13 vs .travis.yml in stackprof-0.2.14

@@ -5,10 +5,9 @@
 
 language: general
 
 env:
   matrix:
-    - RVM_RUBY_VERSION=2.1
     - RVM_RUBY_VERSION=2.2
     - RVM_RUBY_VERSION=2.3
     - RVM_RUBY_VERSION=2.4
     - RVM_RUBY_VERSION=2.5
     - RVM_RUBY_VERSION=2.6