Enable Rohde&Schwarz ZNLE VNA

[FKMalina]

This pull request includes minor changes to Rohde&Schwarz VNA driver, making it compatible with a family of the budget R&S VNA (ZNLE).

[jenshnielsen]

@FKMalina Thanks for the contribution. Looks good. Please fix the small issues pointed out by the precommit hooks and my inline comment and then this should be good to merge

[codecov]

Codecov Report

Attention: Patch coverage is 78.57143% with 3 lines in your changes missing coverage. Please review.

Project coverage is 69.38%. Comparing base (120545f) to head (c1696fb).
Report is 27 commits behind head on main.

Files with missing lines	Patch %	Lines
src/qcodes/instrument_drivers/rohde_schwarz/ZNB.py	0.00%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6796   +/-   ##
=======================================
  Coverage   69.37%   69.38%           
=======================================
  Files         340      341    +1     
  Lines       31341    31355   +14     
=======================================
+ Hits        21744    21755   +11     
- Misses       9597     9600    +3     

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