Mandatory heads-up for those that haven't come across them: gogs [0] and its fork gitea [1] are zero config, download-and-run, self-hosted alternatives to GitHub/BitBucket/GitLab that won't suck the life out of your server, are efficiently written, and very fast even on underpowered (read: RPi) hardware or shared VPS nodes.
0: https://gogs.io/
1: https://gitea.io/en-US/