fix(cache): bump cache keys to surface 6 new chain benches

[Flotapponnier]

Summary

• Bumps bench-unfiltered-v53 → v54 and all-benchmarks-v56 → v57
• PR feat(rpc): add NEAR, Flow, Hedera, CKB, MultiversX, NEO benches 216-221 #2002 merged 6 new chain benches (NEAR, Flow, Hedera, CKB, MultiversX, NEO) to main but the cache keys were not bumped in lockstep
• As a result: list_benchmarks serves a stale list (none of the 6 new benches appear in the index), and hedera-rpc is permanently dropped from the cache because it had an em dash at cache-build time (since fixed in 82137e5)

Test plan

• After merge + Vercel deploy, verify get_benchmark("hedera-rpc") no longer returns unknown_slug
• Verify all 6 slugs appear in list_benchmarks response

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