v7.3.1

Upgrade priority: Low. Maintenance upgrade, tracking the latest @polkadot libraries.

Changes:

• Extend support for WrapperKeepOpaque with internal decoding (allowed to fail)
• Adjust max-entries in historic provider LRU
• Update to latest Substrate/Polkadot/Kusama metadata
• Update @polkadot/util to 8.3.1
• Update package paths under ESM