To allow conversions to RHEL 8.6 after its clones, namely Oracle Linux, are released we need to add 8.6 to the hardcoded releasever mapping:

https://github.com/oamg/convert2rhel/blob/v0.25/convert2rhel/systeminfo.py#L40

When we're at it, let's add minor versions all the way out to 8.10 as well as the RHEL 8 release schedule is publicly known https://access.redhat.com/support/policy/updates/errata#Maintenance_Support_2_Phase.