add created and last_updated field to Team, Area and Membership

[struan]

Mostly because it's likely to be handy for debugging things.

[codecov[bot]]

Codecov Report

Merging #61 (2807a6d) into main (19e8c8c) will increase coverage by 0.43%. The diff coverage is 100.00%.

:exclamation: Current head 2807a6d differs from pull request most recent head 7be7dde. Consider uploading reports for the commit 7be7dde to get more accurate results

@@            Coverage Diff             @@
##             main      #61      +/-   ##
==========================================
+ Coverage   76.55%   76.98%   +0.43%     
==========================================
  Files          35       36       +1     
  Lines         951      969      +18     
  Branches       52       52              
==========================================
+ Hits          728      746      +18     
  Misses        209      209              
  Partials       14       14              

Impacted Files	Coverage Δ
neighbourhood/admin.py	76.00% <100.00%> (+1.71%)	:arrow_up:
...od/migrations/0018_add_last_updated_and_created.py	100.00% <100.00%> (ø)
neighbourhood/models.py	85.96% <100.00%> (+0.77%)	:arrow_up:
neighbourhood_warmth/settings.py	100.00% <100.00%> (ø)