Bump mysql2 from 0.4.10 to 0.5.0

Bumps [mysql2](https://github.com/brianmario/mysql2) from 0.4.10 to 0.5.0.
- [Release notes](https://github.com/brianmario/mysql2/releases)
- [Changelog](https://github.com/brianmario/mysql2/blob/master/CHANGELOG.md)
- [Commits](https://github.com/brianmario/mysql2/compare/0.4.10...0.5.0)

Signed-off-by: dependabot[bot] <support@dependabot.com>

Gemfile

@@ -5,7 +5,7 @@ gem "rails", "~> 5.1"
 
 gem "unicorn"
 
-gem "mysql2", "~> 0.3.20"
+gem "mysql2", "~> 0.5.0"
 
 # uncomment to use PostgreSQL
 # gem "pg"

Gemfile.lock

@@ -78,7 +78,7 @@ GEM
     mini_mime (1.0.0)
     mini_portile2 (2.3.0)
     minitest (5.11.3)
-    mysql2 (0.3.21)
+    mysql2 (0.5.0)
     nio4r (2.3.0)
     nokogiri (1.8.2)
       mini_portile2 (~> 2.3.0)
@@ -174,7 +174,7 @@ DEPENDENCIES
   json
   machinist
   mail
-  mysql2 (~> 0.3.20)
+  mysql2 (~> 0.5.0)
   nokogiri (>= 1.7.2)
   oauth
   rails (~> 5.1)