fix: changes for HA core 2022.4

[firstof9]

Proposed change

Make the mail_updated sensor properly use datetime object for HA core 2022.4

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

[codecov-commenter]

Codecov Report

Merging #644 (5d5539c) into dev (88e709f) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##              dev     #644   +/-   ##
=======================================
  Coverage   98.33%   98.33%           
=======================================
  Files           7        7           
  Lines        1379     1382    +3     
=======================================
+ Hits         1356     1359    +3     
  Misses         23       23           

Impacted Files	Coverage Δ
custom_components/mail_and_packages/const.py	100.00% <100.00%> (ø)
custom_components/mail_and_packages/helpers.py	98.66% <100.00%> (-0.01%)	⬇️
custom_components/mail_and_packages/sensor.py	98.29% <100.00%> (+0.06%)	⬆️