(fix): fixed tcpip_keepalive for TCPIPSocketSession (#396)

[oliverpetschick]

Hi,

fixes #396 deprecated attribute ".sock" for TCPIPSocketSessions.

I've also included type hints for the self.interface classes, making it easier to detect such issues promptly. After implementing this change, I tested it with the same code block that initially triggered the error, and it executed as intended.

• Closes Attribute Error when setting VI_ATTR_TCPIP_KEEPALIVE to True #396
• Executed black . && isort -c . && flake8 with no errors
• The change is fully covered by automated unit tests
• Documented in docs/ as appropriate
• Added an entry to the CHANGES file

[codecov]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (79fd091) 23.14% compared to head (3494e6f) 23.14%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #397   +/-   ##
=======================================
  Coverage   23.14%   23.14%           
=======================================
  Files          23       23           
  Lines        3318     3318           
  Branches      458      458           
=======================================
  Hits          768      768           
  Misses       2533     2533           
  Partials       17       17           

Flag	Coverage Δ
unittests	23.14% <0.00%> (ø)

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Files	Coverage Δ
pyvisa_py/tcpip.py	20.47% <0.00%> (ø)

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[oliverpetschick]

I reverted the type hints since mypy does not allow the assignment of = None to predefined types.

[MatthieuDartiailh]

It is a bit sad, I liked those. Anyway thanks for the patch. I will merge and I will cut a new release either tonight or next week.