pr_6528.prdoc

title: 'TransactionPool API uses async_trait'
doc:
- audience: Node Dev
  description: |-
    This PR refactors `TransactionPool` API to use `async_trait`, replacing the` Pin<Box<...>>` pattern. This should improve readability and maintainability.

    The change is not altering any functionality.
crates:
- name: sc-rpc-spec-v2
  bump: minor
- name: sc-service
  bump: minor
- name: sc-transaction-pool-api
  bump: major
- name: sc-transaction-pool
  bump: major
- name: sc-rpc
  bump: minor