remove Ubuntu 18.04 as supported OS (#402) #228

Job	Run time
Puppet / Static validations	32s
Puppet / 8 (Ruby 3.2)	55s
Puppet / Puppet 8 - CentOS 9	1m 29s
Puppet / 7 (Ruby 2.7)	1m 17s
Puppet / Puppet 7 - CentOS 9	1m 25s
Puppet / Puppet 8 - OracleLinux 8	1m 52s
Puppet / Puppet 7 - OracleLinux 8	2m 1s
Puppet / Puppet 8 - OracleLinux 9	1m 31s
Puppet / Puppet 7 - OracleLinux 9	1m 32s
Puppet / Puppet 8 - Debian 11	1m 41s
Puppet / Puppet 7 - Debian 11	1m 38s
Puppet / Puppet 8 - Debian 12	1m 43s
Puppet / Puppet 7 - Debian 12	1m 33s
Puppet / Puppet 8 - Ubuntu 20.04	1m 50s
Puppet / Puppet 7 - Ubuntu 20.04	1m 51s
Puppet / Puppet 8 - Ubuntu 22.04	1m 50s
Puppet / Puppet 7 - Ubuntu 22.04	1m 39s
Puppet / Distro Puppet - Archlinux rolling	1m 41s
Puppet / Test suite	1s
	28m 1s

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