Travis CI matrix add Ruby 2.5 and switch Mac OS X to Ruby 2.3 (ala High Sierra)

Author: sodabrew

.travis.yml

@@ -5,7 +5,7 @@ bundler_args: --without benchmarks development
 # Pin Rubygems to a working version. Sometimes it breaks upstream. Update now and then.
 before_install:
   - gem --version
-  - gem update --system 2.6.12
+  - gem update --system 2.7.3
   - gem update bundler
   - gem --version
   - bash .travis_setup.sh
@@ -18,6 +18,7 @@ addons:
     - mysql-client-core-5.6
     - mysql-client-5.6
 rvm:
+  - 2.5
   - 2.4
   - 2.3
   - 2.2
@@ -72,7 +73,7 @@ matrix:
         hosts:
           - mysql2gem.example.com
     - os: osx
-      rvm: system
+      rvm: 2.3
       env: DB=mysql56
       addons:
         hosts:
@@ -86,7 +87,7 @@ matrix:
   allow_failures:
     - rvm: ruby-head
     - os: osx
-      rvm: system
+      rvm: 2.3
       env: DB=mysql56
     - rvm: 2.0.0
       env: DB=mysql51

README.md

@@ -523,7 +523,7 @@ As for field values themselves, I'm workin on it - but expect that soon.
 
 This gem is tested with the following Ruby versions on Linux and Mac OS X:
 
- * Ruby MRI 2.0.0, 2.1.x, 2.2.x, 2.3.x, 2.4.x
+ * Ruby MRI 2.0.0, 2.1.x, 2.2.x, 2.3.x, 2.4.x, 2.5.x
  * Rubinius 2.x and 3.x do work but may fail under some workloads
 
 This gem is tested with the following MySQL and MariaDB versions: