Bump selenium-webdriver from 3.11.0 to 3.12.0

Bumps [selenium-webdriver](https://github.com/SeleniumHQ/selenium) from 3.11.0 to 3.12.0.
- [Release notes](https://github.com/SeleniumHQ/selenium/releases)
- [Changelog](https://github.com/SeleniumHQ/selenium/blob/master/rb/CHANGES)
- [Commits](SeleniumHQ/selenium@selenium-3.11.0...selenium-3.12.0)

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

Gemfile.lock

@@ -95,7 +95,7 @@ GEM
     sawyer (0.8.1)
       addressable (>= 2.3.5, < 2.6)
       faraday (~> 0.8, < 1.0)
-    selenium-webdriver (3.11.0)
+    selenium-webdriver (3.12.0)
       childprocess (~> 0.5)
       rubyzip (~> 1.2)
     sequel (5.8.0)