Curations use `commit` instead of `tree` for GitHub source urls

[capfei]

Harvested data shows uses tree for GitHub source location, but when you submit a curation to edit the source location, it changes to commit. According to this PR, it looks like the website uses the Harvest UI picker, which uses commit. Everything else I could fine uses tree.
6d1bc7d

• Harvested source location:
  • https://clearlydefined.io/definitions/git/github/mono/mono/abad3612068e7333956106e7be02d9ce9e346f92
• Curated source location:
  • https://clearlydefined.io/definitions/sourcearchive/mavencentral/org.apache.httpcomponents/httpcore-nio/4.4.15/4.4.15