Don't run build evmos twice in CI

[adlerjohn]

Currently, the build-evmos workflow runs twice on each push to a PR, since it's configured to run both on push and on PR: https://github.com/celestiaorg/optimint/blob/404e426e46f6c462c890aecc04262e1f91f3052d/.github/workflows/build-evmos.yml#L4-L11

Suggest using the following on: https://github.com/FuelLabs/sway/blob/f2581f43523bed51aaefa5a416d2d7f4051dc2f2/.github/workflows/ci.yml#L3-L9