add note about bcrypt vs. passlib/libpass

radicale/auth/htpasswd.py

@@ -43,7 +43,7 @@ out-of-the-box:
     - SHA256     (htpasswd -2 ...)
     - SHA512     (htpasswd -5 ...)
 
-When bcrypt is installed:
+When bcrypt is installed (bcrypt >= 5.0.0 requires passlib/libpass >= 1.9.3):
     - BCRYPT     (htpasswd -B ...) -- Requires htpasswd 2.4.x
 
 When argon2 is installed: