Fixes and tweaks

[ouziel-slama]

• Return "no implemented" error when trying to get info about RPS transactions
• Fix typo in `protocol_changes.json' for testnet4
• sat_per_vbyte parameter accepts float
• Don't retry to get vin info when parsing mempool
• Add stacktrace when warning from bitcoind

---

• Double-check the spelling and grammar of all strings, code comments, etc.
• Double-check that all code is deterministic that needs to be
• Add tests to cover any new or revised logic
• Ensure that the test suite passes
• Update the project release notes
• Update the project documentation, as appropriate, with a corresponding Pull Request in the Documentation repository

[github-advanced-security]

pylint found more than 20 potential problems in the proposed changes. Check the Files changed tab for more details.