Update omnibus gem to fix ruby 2.7

Updated includes patch that fixes building omnibus projects using ruby
2..7

Gemfile

@@ -2,7 +2,7 @@ source 'https://rubygems.org'
 require_relative "lib/gitlab/version"
-omnibus_gem_version = Gitlab::Version.new('omnibus', "7.0.10.02")
+omnibus_gem_version = Gitlab::Version.new('omnibus', "7.0.10.03")
 # Note that omnibus is from a fork with additional gitlab changes.  You can
 # check what they are with the following comparison link:

Gemfile.lock

 GIT
   remote: https://dev.gitlab.org/gitlab/omnibus.git
-  revision: c33184c00a1774f8350f0f1d8cbce35b99a82fd1
-  tag: 7.0.10.02
+  revision: 996ed5ed05d97bbb0c73f2f890a1e15887a9749e
+  tag: 7.0.10.03
   specs:
     omnibus (7.0.10)
       aws-sdk-s3 (~> 1)