chore: upgrade to fuels v0.50

[ra0x3]

Thanks for opening a PR with the Fuel Indexer project. Please review the Checklist below and ensure you've completed all of the necessary steps to make this PR review as painless as possible.

Checklist

• [ ] Ensure your top-level commit message is in line with our contributor guidelines.
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Description

• PR upgrades us to fuels v0.50 and some fuel-core crates pinned to v0.35.4

Testing steps

• [ ] CI should pass

Changelog

• chore: upgrade to fuels v0.50