add bitcoin core 29 release candidate and testing guide

Author: vnprc

_posts/2025-04-09-socratic-seminar-39.md

@@ -24,6 +24,8 @@ Please note the meeting location at Fidelity Investments near RTP.
 - introductions
 
 # Bitcoin Core
+- [Bitcoin Core 29.0rc3](https://bitcoincore.org/bin/bitcoin-core-29.0/)
+  - [Testing Guide](https://github.com/bitcoin-core/bitcoin-devwiki/wiki/29.0-Release-Candidate-Testing-Guide)
 - This [tracking PR for IBD speedup improvements](https://github.com/bitcoin/bitcoin/pull/32043) shows some surprising progress! E.G.
   - [30% speedup for pruned nodes](https://github.com/bitcoin/bitcoin/pull/28280)
   - [30% speedup for low memory nodes](https://github.com/bitcoin/bitcoin/pull/30039)