lscsoft-lalsuite-dev: remove all python2 packages
This MR removes all python2 package references from the lscsoft-lalsuite-dev metapackage, and updates the python3 package references for rpm to work on both el7 and el8.
Maintenance will be performed on git.ligo.org, containers.ligo.org, and docs.ligo.org on Tuesday 23 April 2024 starting at approximately 9am PDT. It is expected to take around twenty minutes and there will be several periods of downtime throughout the maintenance. Please address any comments, concerns, or questions to the helpdesk.
This MR removes all python2 package references from the lscsoft-lalsuite-dev metapackage, and updates the python3 package references for rpm to work on both el7 and el8.