Drop a constant that is not used anywhere

This is unused and thus can be removed.

Author: pradyunsg

tests/test_traceback.py

@@ -9,8 +9,6 @@
 from rich.theme import Theme
 from rich.traceback import Traceback, install
 
-CAPTURED_EXCEPTION = 'Traceback (most recent call last):\n╭──────────────────────────────────────────────────────────────────────────────────────────────────╮\n│ File "/Users/textualize/projects/rich/tests/test_traceback.py", line 26, in test_handler        │\n│    23     try:                                                                                   │\n│    24         old_handler = install(console=console, line_numbers=False)                         │\n│    25         try:                                                                               │\n│  ❱ 26             1 / 0                                                                          │\n│    27         except Exception:                                                                  │\n│    28             exc_type, exc_value, traceback = sys.exc_info()                                │\n│    29             sys.excepthook(exc_type, exc_value, traceback)                                 │\n╰──────────────────────────────────────────────────────────────────────────────────────────────────╯\nZeroDivisionError: division by zero\n'
-
 
 def test_handler():
     console = Console(file=io.StringIO(), width=100, color_system=None)