Bitcoin Core 0.17 rc3 - for testing PSBT and ColdCard integration

[FrancisPouliot]

https://github.com/bitcoin/bitcoin/releases/tag/v0.17.0rc3

We are trying to test the concept of having a chron docker batching transactions based on configurations choser by a Bitcoin node operator, and aggregating them for signature in coldcard periodically.

This version of Bitcoin has the RPC call list in it so we can start testing it.

[FrancisPouliot]

This is the new RPC call list for PSBT https://github.com/bitcoin/bitcoin/blob/838b85e120fd7957cf4abce0905d3aff96fa7278/src/rpc/rawtransaction.cpp#L1700