fix: include std feature on strum dependency

[deekerno]

Description

Includes std feature for strum in fuel-indexer-api-server.

Testing steps

For some odd reason, I was unable to build the fuel-indexer package due to the following error:

error[E0599]: the method `as_dyn_error` exists for reference `&ParseError`, but its trait bounds were not satisfied
   --> packages/fuel-indexer-api-server/src/api.rs:105:18
    |
105 |     ParseError(#[from] strum::ParseError),
    |                  ^^^^ method cannot be called on `&ParseError` due to unsatisfied trait bounds
    |

Try to build on develop, and then try to build on this branch; you should see that it works in the latter.

[ra0x3]

utACK