Issue 49603 - 389-ds-base package rebuilt on EPEL can't be installed due to missing dependencies
    
    Bug Description:
    On EPEL python3 packages are not built, but still mentioned in Requires.
    This prevents 389-ds-base from being installed.
    
    Fix Description:
    Require python3-lib389 only on Fedora and EPEL > 7. Additionally fix
    conditionals according to packaging guidelines.
    
    https://pagure.io/389-ds-base/issue/49603
    
    Reviewed by: mreynolds (Thanks!)