v15.3.1

• Set typegen scripts for Docs to use v15 (#6060)
• Add Asset hub options to polkadot-types-internal-metadata (#6062)
• Add metadataVer cli arg for polkadot-types-internal-metadata, and ensure backwards compatibility with v14 (#)
  • This adds --metadataVer to polkadot-types-internal-metadata. It is meant to be used along side --endpoint which will allow for the use of metadata versions above v14.