fix "belay new" CLI command

[BrianPugh]

Previously the belay new CLI command was broken in some installed because there would be a __pycache__ directory in the template directory. These files are now ignored.

[codecov]

Codecov Report

Attention: Patch coverage is 7.14286% with 13 lines in your changes missing coverage. Please review.

Project coverage is 70.19%. Comparing base (b477778) to head (c7bec71).

Files	Patch %	Lines
belay/device.py	0.00%	0 Missing and 7 partials ⚠️
belay/cli/new.py	25.00%	3 Missing ⚠️
belay/executers.py	0.00%	0 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #164      +/-   ##
==========================================
- Coverage   70.82%   70.19%   -0.64%     
==========================================
  Files          39       39              
  Lines        1714     1701      -13     
  Branches      379      379              
==========================================
- Hits         1214     1194      -20     
+ Misses        426      418       -8     
- Partials       74       89      +15     

Flag	Coverage Δ
unittests	70.13% <7.14%> (-0.46%)	⬇️

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