Update to new Backend API

[GDYendell]

Fixes #16

[codecov]

Codecov Report

Attention: Patch coverage is 28.57143% with 5 lines in your changes missing coverage. Please review.

Project coverage is 68.82%. Comparing base (03c7030) to head (eda516c).
Report is 3 commits behind head on main.

Files	Patch %	Lines
src/eiger_fastcs/__main__.py	0.00%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #44      +/-   ##
==========================================
- Coverage   71.16%   68.82%   -2.35%     
==========================================
  Files           4        4              
  Lines         274      263      -11     
==========================================
- Hits          195      181      -14     
- Misses         79       82       +3     

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