You have some problems in your Pi-hole, and these are likely affecting your ability to run updates.
Github.com is not commonly found on any reliable blocklists.
You are running blocklists (adlists) that are not properly formatted for Pi-hole. Support for easylist formats was dropped several versions ago, because they cause false positives. When you use these improperly formatted lists, the domain parsing is not reliable and you end up with false positives.
https://easylist.to/easylist/fanboy-annoyance.txt
https://easylist.to/easylist/fanboy-annoyance.txt
https://easylist.to/easylist/fanboy-social.txt
If you look at the complete output of pihole -g, you will see the high number of errors for these lists. Delete these lists from your adlists and rebuild gravity.