flexible ruby-oci8 version specification. [Gaurav Sharma]

Follow up to rails#15109.

/cc @Gaurav2728

Author: senny

Gemfile

@@ -86,7 +86,7 @@ end
 # gems that are necessary for ActiveRecord tests with Oracle database
 if ENV['ORACLE_ENHANCED']
   platforms :ruby do
-    gem 'ruby-oci8', '~> 2.1.0'
+    gem 'ruby-oci8', '~> 2.1'
   end
   gem 'activerecord-oracle_enhanced-adapter', github: 'rsim/oracle-enhanced', branch: 'master'
 end