Bump version to 10.5.0

Gemfile.lock

 PATH
   remote: .
   specs:
-    gitlab-exporter (10.4.0)
+    gitlab-exporter (10.5.0)
       connection_pool (= 2.2.5)
       pg (= 1.2.3)
       puma (= 5.3.2)

lib/gitlab_exporter/version.rb

 module GitLab
   module Exporter
-    VERSION = "10.4.0".freeze
+    VERSION = "10.5.0".freeze
   end
 end