refactor: less amazon forwarding email validation

[firstof9]

Proposed change

Use less validation on amazon forwarding email entries.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (which adds functionality)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests
• Documentation update
• Adds a new shipper
• Update existing shipper

Additional information

• This PR is related to issue: n/a

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.52%. Comparing base (8608d22) to head (6c3a2a5).
Report is 32 commits behind head on dev.

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Additional details and impacted files

@@            Coverage Diff             @@
##              dev     #960      +/-   ##
==========================================
- Coverage   95.07%   93.52%   -1.55%     
==========================================
  Files           8        8              
  Lines        1482     1561      +79     
==========================================
+ Hits         1409     1460      +51     
- Misses         73      101      +28     

Files	Coverage Δ
custom_components/mail_and_packages/config_flow.py	92.88% <100.00%> (-7.12%)	⬇️

... and 3 files with indirect coverage changes