Fix a pytest warning about an invalid escape sequence (#1360)

Author: tleonhardt

tests/test_transcript.py

@@ -49,8 +49,8 @@ def __init__(self, *args, **kwargs):
     speak_parser.add_argument('-p', '--piglatin', action="store_true", help="atinLay")
     speak_parser.add_argument('-s', '--shout', action="store_true", help="N00B EMULATION MODE")
 
-    # Escape open bracket since help text can contain markup
-    speak_parser.add_argument('-r', '--repeat', type=int, help="output \[n] times")
+    # Escape open bracket since help text can contain rich markup
+    speak_parser.add_argument('-r', '--repeat', type=int, help=r"output \[n] times")
 
     @cmd2.with_argparser(speak_parser, with_unknown_args=True)
     def do_speak(self, opts, arg):