Bug with the parameter "last_modified" in the method "list" of tenable.io scans.py

[megavexus]

Describe the bug
Sin this change, a few weeks ago, the method "list" of "scans.py" of "Tenable IO" is not working with the parameter "last_modified".

To Reproduce
Steps to reproduce the behavior:

1. Call the method "list" of scans.py of the library "io"
2. Add a paramether with a datetime:

list_scans = api.scans.list(
            last_modified=datetime.today()
)

4. See error:

  File "XXXX/site-packages/tenable/io/scans.py", line 1205, in list
    lm = int(time.mktime(last_modified).timetuple())
AttributeError: 'float' object has no attribute 'timetuple'

Expected behavior
A clear and concise description of what you expected to happen.

System Information (please complete the following information):

• OS: Ubuntu budgie
• Architecture: 64bit
• Version 22.04
• Memory 16GB

Additional context
To fix it, you only have to replace the affected line with:

     lm = int(time.mktime(start_time.timetuple()))

[SteveMcGrath]

As you are already aware of the issue and the fix, do you want to file a PR to fix as well?