fix: Check non-deleted events before user deletion

[iamareebjamal]

Fixes fossasia/open-event-frontend#5633

[codecov]

Codecov Report

Merging #7448 (3f51a11) into development (28a0c03) will decrease coverage by 0.00%.
The diff coverage is 0.00%.

@@               Coverage Diff               @@
##           development    #7448      +/-   ##
===============================================
- Coverage        65.35%   65.34%   -0.01%     
===============================================
  Files              265      265              
  Lines            13225    13226       +1     
===============================================
  Hits              8643     8643              
- Misses            4582     4583       +1     

Impacted Files	Coverage Δ
app/api/users.py	31.49% <0.00%> (-0.18%)	⬇️

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