Bump version to 7.0.3

- Bumps the gem version to 7.0.3

Related https://gitlab.com/gitlab-org/gitlab-exporter/-/issues/70

Signed-off-by: Robert Marshall <rmarshall@gitlab.com>

Gemfile.lock

 PATH
   remote: .
   specs:
-    gitlab-exporter (7.0.2)
+    gitlab-exporter (7.0.3)
       connection_pool (~> 2.2.1)
       pg (~> 1.1)
       quantile (~> 0.2.0)

lib/gitlab_exporter/version.rb

 module GitLab
   module Exporter
-    VERSION = "7.0.2".freeze
+    VERSION = "7.0.3".freeze
   end
 end