Update Celestia Chain version used in CI to `v2.1.2`

[ljoss17]

Commit

f2d4e7f

Proposal

Update the version of Celestia Chain used in the CI.

• Current version: v1.14.0

  hermes/flake.lock

  Line 80 in f2d4e7f

  "ref": "v1.14.0",

• Latest 05.08.2024: v2.1.2 taken from https://github.com/celestiaorg/celestia-app/releases

---

For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate milestone (priority) applied
• Appropriate contributors tagged
• Contributor assigned/self-assigned