Release of 7.3.0

• Removed support for Puppet 5
• Ensured support for Puppet 7 in requirements and stdlib
• Fix minor error in compliance_markup data
• Added EL8 support
• Added check for hidepid on /proc. If it is on, update the systemd-logind service
  entry to include the hidepid group as a supplementary group and restart the
  systemd-logind service.
• Added pam access entry for gdm user so greeter session can start.
• Added error message if gdm version older than 3.0 is used.
• Added the following parameters:
  gdm::pam - indicates if pam is controlled by simp. If this is set to
  true then a pam access rule is added to allow the gdm user
  local access to the system. Defaults to simp_options::pam.
  gdm::display_mgr_user - the name of the user that the gdm service will run under.
  Defaults to 'gdm'
• simp/gnome and simp/auditd were removed from the dependencies
  in metadata.json.
• simp/pam was added to optional dependencies and is needed if gdm:pam
  is set to true.
• removed pulseaudio from list of packages because gdm has dependency on it
  so it will automatically be installed.