Bugfix: Removes incorrect assert from update_df and add more robust tests

[sandresen1]

No description provided.

[codecov]

Codecov Report

Merging #1250 (731d70c) into develop (600bf99) will increase coverage by 0.00%.
Report is 1 commits behind head on develop.
The diff coverage is 100.00%.

❗ Current head 731d70c differs from pull request most recent head 89bc2e7. Consider uploading reports for the commit 89bc2e7 to get more accurate results

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #1250   +/-   ##
========================================
  Coverage    76.48%   76.49%           
========================================
  Files           61       61           
  Lines         5379     5381    +2     
========================================
+ Hits          4114     4116    +2     
  Misses        1265     1265           

Files	Coverage Δ
macrosynergy/management/utils/df_utils.py	93.99% <100.00%> (+0.03%)	⬆️

... and 1 file with indirect coverage changes