fix: delete plain fields

[SKairinos]

This change is 

[codecov]

Codecov Report

❌ Patch coverage is 65.09804% with 178 lines in your changes missing coverage. Please review.
✅ Project coverage is 76.59%. Comparing base (8eec23e) to head (0c78f95).
⚠️ Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
codeforlife/pprint.py	0.00%	88 Missing ⚠️
...er/management/commands/encrypt_plaintext_fields.py	0.00%	67 Missing ⚠️
codeforlife/user/models/user/user.py	82.81%	11 Missing ⚠️
codeforlife/user/models/other.py	81.25%	3 Missing ⚠️
codeforlife/user/models/klass.py	91.30%	2 Missing ⚠️
codeforlife/__init__.py	0.00%	1 Missing ⚠️
codeforlife/models/fields/data_encryption_key.py	90.90%	1 Missing ⚠️
codeforlife/models/fields/sha256.py	97.43%	1 Missing ⚠️
codeforlife/models/signals/general.py	83.33%	1 Missing ⚠️
codeforlife/settings/custom.py	0.00%	1 Missing ⚠️
... and 2 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #177      +/-   ##
==========================================
+ Coverage   76.11%   76.59%   +0.47%     
==========================================
  Files         191      191              
  Lines        5502     5196     -306     
==========================================
- Hits         4188     3980     -208     
+ Misses       1314     1216      -98     

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