change: Making _BreakSignal and _ContinueSignal public exceptions

[jheckey]

Issue #, if available:

Description of changes:

Changing _BreakSignal and _ContinueSignal to be public exception classes

Testing done:

Updated tests, reran

Merge Checklist

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General

• I have read the CONTRIBUTING doc
• I used the commit message format described in CONTRIBUTING
• I have updated any necessary documentation, including READMEs and API docs (if appropriate)

Tests

• I have added tests that prove my fix is effective or that my feature works (if appropriate)
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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (e12f376) to head (3429bbe).

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #381   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           49        49           
  Lines         4882      4884    +2     
  Branches       561       561           
=========================================
+ Hits          4882      4884    +2     

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