Describe the bug:
When using the option use_elastic_excepthook every uncaught exception also produces the following TypeError:

Error in sys.excepthook:
TypeError: _excepthook() takes 1 positional argument but 4 were given

To Reproduce

Run the following Python snippet

import elasticapm


def run():
    raise Exception("hello")

client = elasticapm.Client(
    {"SERVICE_NAME": "test"},
    use_elastic_excepthook=True,
)
run()

It will produce this output:

Error in sys.excepthook:
TypeError: _excepthook() takes 1 positional argument but 4 were given

Original exception was:
Traceback (most recent call last):
  File "t.py", line 13, in <module>
    run()
  File "t.py", line 5, in run
    raise Exception("hello")
Exception: hello

Environment (please complete the following information)

• OS: MacOS 10.15.3
• Python version: 3.8.5
• Agent version: 6.0.0

Additional context

The problem seems to be with the function signature of the Client._excepthook function that is used to override the sys.excepthook.

The sys.excepthook expects three arguments (type, value, traceback), while the Client._excepthook only expects the self argument.