chore: upgrade to bootstrap 5

[dpgaspar]

Description

Bootstrap 5 upgrade!! initial take

ADDITIONAL INFORMATION

• [ ] Has associated issue:
• [ ] Is CRUD MVC related.
• [ ] Is Auth, RBAC security related.
• [ ] Changes the security db schema.
• [ ] Introduces new feature
• [ ] Removes existing feature

[codecov[bot]]

Codecov Report

Merging #2146 (7c96eb3) into master (3cfe13f) will increase coverage by 0.10%. The diff coverage is 50.00%.

@@            Coverage Diff             @@
##           master    #2146      +/-   ##
==========================================
+ Coverage   78.55%   78.65%   +0.10%     
==========================================
  Files          72       72              
  Lines        8695     8695              
==========================================
+ Hits         6830     6839       +9     
+ Misses       1865     1856       -9     

Flag	Coverage Δ
python	78.65% <50.00%> (+0.10%)	:arrow_up:

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Files	Coverage Δ
flask_appbuilder/menu.py	94.28% <50.00%> (ø)

... and 3 files with indirect coverage changes