make payment price sync on order delete DOT-263

[marcelwk]

Description of changes

Fix of #2887

Added decorator to make price sync function also when order is deleted, and not only when new order is created.
Otherwise the price shown in UI and price sent to Stripe diverge after order is deleted

Code Checklist

• I have added tests
• I have provided documentation

[marcelwk]

Have not been able to set up the dev-env to test the fix. I would be grateful if someone could test it, and optionally create a test for the order-removal case.

[marcelwk]

@henrikskog, ping because you're the issue author

[codecov]

Codecov Report

Merging #2978 (3e40858) into main (2a8aea3) will increase coverage by 0.06%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #2978      +/-   ##
==========================================
+ Coverage   78.60%   78.66%   +0.06%     
==========================================
  Files         338      338              
  Lines       14939    14940       +1     
==========================================
+ Hits        11743    11753      +10     
+ Misses       3196     3187       -9     

Files	Coverage Δ
apps/webshop/signals.py	100.00% <100.00%> (ø)

... and 2 files with indirect coverage changes

[linear]

DOT-263 Billed for wrong items in webshop

Is the webshop being used? If so this should probably be looked into.

From github issue (#2887):
Describe the bug
People are being billed for items not chosen when buying items. One of ways in which the bug can occur: selecting an item, then unselecting it. If you then go to buy something else, you will also be billed for the item you selected then unselected.

There has been multiple bug reports for this. This is the latest one:

“Heisann! Det kan virke som problemet med overbetaling om man fjerner en artikkel fra webshop-handlekurven fortsatt ikke er borte 😅 Er en som fjernet en sløyfe når vedkommende skulle kjøpe ølglass og ble alikevell fakturert for sløyfen i stripe, men registrert for kun ølglassene 🙈”

To Reproduce
Steps to reproduce the behavior:

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior

• Users should only be billed for the items that are in their cart when pressing buy!!

Screenshots
If applicable, add screenshots to help explain your problem.

[henrikskog]

Sorry for reviewing so late, but thank you so much for the PR! I ran it locally and as far as I can tell it now syncs correctly.