bugfix AttributeError, stdin has no attribute, 'isatty'

[jquast]

Closes #148

[codspeed]

Merging this PR will not alter performance

✅ 18 untouched benchmarks

---

_{Comparing bugfix/stdin-none-no-console (66187f4) with master (02d9722)}

[codecov]

Codecov Report

❌ Patch coverage is 93.33333% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 92.65%. Comparing base (02d9722) to head (66187f4).

Files with missing lines	Patch %	Lines
telnetlib3/client.py	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #149      +/-   ##
==========================================
+ Coverage   92.64%   92.65%   +0.01%     
==========================================
  Files          28       28              
  Lines        7260     7272      +12     
  Branches     1269     1271       +2     
==========================================
+ Hits         6726     6738      +12     
  Misses        341      341              
  Partials      193      193              

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