Merge bitcoin/bitcoin#31526: doc: Install net/py-pyzmq port on FreeBSD for interface_zmq.py

0a76c29 doc: Install `net/py-pyzmq` port on FreeBSD for `interface_zmq.py` (Hennadii Stepanov)

Pull request description:

  On FreeBSD, Python's `zmq` module is provided as a separate port.

  This PR updates the FreeBSD Build Guide to include this port, enabling the `interface_zmq.py` functional test.

ACKs for top commit:
  maflcko:
    lgtm ACK 0a76c29
  vasild:
    ACK 0a76c29

Tree-SHA512: c13eada3e870149f47348145d6a29f41125ac75efd88eabe6dd2d0429e0377ed280e76a764cfaf627498c1d07b9135a995cc644146fa666bc3bfa0eb2c86e88b

Author: fanquake

doc/build-freebsd.md

@@ -96,7 +96,7 @@ There is an included test suite that is useful for testing code changes when dev
 To run the test suite (recommended), you will need to have Python 3 installed:
 
 ```bash
-pkg install python3 databases/py-sqlite3
+pkg install python3 databases/py-sqlite3 net/py-pyzmq
 ```
 ---