Fix Travis CI

DanielKuhn · DanielKuhn · commit 79119b19875c · 2019-08-01T15:57:09.000+02:00
By specifying MySQL service in config file.
diff --git a/.travis.yml b/.travis.yml
@@ -8,3 +8,6 @@ cache: bundler
 
 script:
   - bin/rspec
+
+services:
+  - mysql
