distros: Fix CentOS allowance
Before, with Python 3.6, the pattern was: ('CentOS Linux', '7.9.2009', 'Core')
But after installing Python 3.8 from centos-release-scl it is now ('CentOS Linux', '7', 'Core')
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Before, with Python 3.6, the pattern was: ('CentOS Linux', '7.9.2009', 'Core')
But after installing Python 3.8 from centos-release-scl it is now ('CentOS Linux', '7', 'Core')