Set constraints for images in uploader

[raccube]

Closes #1510
Closes #1511

[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (acf9595) 95.70% compared to head (401498e) 95.71%.

Files	Patch %	Lines
...controllers/settings/profile_picture_controller.rb	50.00%	1 Missing ⚠️
app/uploaders/base_uploader.rb	85.71%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1513   +/-   ##
=======================================
  Coverage   95.70%   95.71%           
=======================================
  Files         174      174           
  Lines        2699     2704    +5     
=======================================
+ Hits         2583     2588    +5     
  Misses        116      116           

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[pixeldesu]

Works fine, but it'd be interesting to see if we could show proper validation errors for the improper files instead of just saying "Unable to update profile".

That might lead people to retry over and over, even though the file is just invalid.