Add "ERROR" level to logging

[shoubhikraj]

AutodE did not previously recognise the ERROR level of logging if set by "export AUTODE_LOG_LEVEL=ERROR".

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Checklist

• [x] The changes include an associated explanation of how/why
• [x] Test pass
• [x] Documentation has been updated
• [x] Update changelog

[codecov[bot]]

Codecov Report

Merging #231 (956eb7e) into v1.3.5 (6813afd) will increase coverage by 0.00%. The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           v1.3.5     #231   +/-   ##
=======================================
  Coverage   97.13%   97.13%           
=======================================
  Files         196      196           
  Lines       20131    20135    +4     
=======================================
+ Hits        19554    19558    +4     
  Misses        577      577           

Flag	Coverage Δ
unittests	97.13% <100.00%> (+<0.01%)	:arrow_up:

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
autode/log/log.py	93.75% <100.00%> (+0.41%)	:arrow_up:
tests/test_log.py	94.44% <100.00%> (+0.69%)	:arrow_up:

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[shoubhikraj]

@t-young31 Thanks! 😄 Happy for you to merge it.