doc: add databases/py-sqlite3 to FreeBSD test suite deps

Author: fanquake

doc/build-freebsd.md

@@ -72,7 +72,7 @@ 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
+pkg install python3 databases/py-sqlite3
 ```
 ---