v1.20.1

• Important RPC for account_nextIndex has been moved to system_accountNextIndex (Aligning with Substrate as a primary alias)
• Cleanup map entries support with only Substrate 2.0-era RPCs (as introduced)
• Add system_dryRun RPC
• Optimize derive.staking.queryMulti retrievals with additional per-type batching
• Add derive.staking.waitingInfo (same as electedInfo for waiting validators)
• Adjust types & metadata for latest Substrate
• @polkadot/util 2.15