fix: handle keyring store exception

[chidiwilliams]

Resolves #679
Resolves #648

[codecov]

Codecov Report

Attention: Patch coverage is 71.42857% with 8 lines in your changes are missing coverage. Please review.

Project coverage is 79.90%. Comparing base (9395492) to head (0e15168).

Files	Patch %	Lines
buzz/widgets/main_window.py	16.66%	5 Missing ⚠️
buzz/store/keyring_store.py	83.33%	2 Missing ⚠️
buzz/cli.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #685      +/-   ##
==========================================
- Coverage   79.93%   79.90%   -0.04%     
==========================================
  Files          81       81              
  Lines        3748     3747       -1     
==========================================
- Hits         2996     2994       -2     
- Misses        752      753       +1     

Flag	Coverage Δ
Linux	73.68% <67.85%> (-0.04%)	⬇️
Windows	81.22% <60.71%> (-0.04%)	⬇️

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