Update readme so it specifies correct ruby version

README.md

@@ -82,7 +82,7 @@ Instructions on how to start GitLab and how to run the tests can be found in the
 GitLab is a Ruby on Rails application that runs on the following software:
 - Ubuntu/Debian/CentOS/RHEL/OpenSUSE
-- Ruby (MRI) 2.7.5
+- Ruby (MRI) 2.7.7
 - Git 2.33+
 - Redis 5.0+
 - PostgreSQL 12+