Change Sponsor: Add change log to sponsors.sponsor object

[oliviasauls]

Location of change
python.org/admin/sponsor - Change Sponsor/ Admin; individual sponsorship dashboard

Describe the solution you'd like

• A way for admin to see changes a sponsor has made to their Sponsor info or Sponsorship
• Notifications sent to admin/PyCon US team when/if sponsors make any changes to their sponsor information/sponsorship

Reason for change
So admin is notified of changes sponsors make such as changing sponsor description, logos, or contact information and these changes can be reflecting when fulfilling sponsor benefits

Priority
2. Medium

Date Needed
Sponsorship Launch

Additional context