v6.2.1

Upgrade priority: Low. Maintenance updates.

Contributed:

• Cater for new asset fee payment extension (Thanks to https://github.com/apopiak)

Changes:

• Extend error messages for malformed queryMulti inputs
• Correctly handle non-map queries passed to queryMulti in map form
• Use new metadata v14 lookup type in derive results
• Adjust definitions to infer TS types in .multi queries
• Fix TS lookup enum generation with nested Option & Tuple
• Bump static metadata for latest Substrate, Polkadot & Kusama