fix: Adds missing reference to the endpoint_url for the S3 proxy

[Nastaliss]

The endpoint_url reference in the method to generate file download URL is missing. This PR fixes that

[codecov[bot]]

Codecov Report

Merging #294 (f7e16d1) into main (4c04a9d) will not change coverage. Report is 2 commits behind head on main. The diff coverage is 0.00%.

@@           Coverage Diff           @@
##             main     #294   +/-   ##
=======================================
  Coverage   95.17%   95.17%           
=======================================
  Files          66       66           
  Lines        1576     1576           
=======================================
  Hits         1500     1500           
  Misses         76       76           

Flag	Coverage Δ
client	100.00% <ø> (ø)
unittests	94.94% <0.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
src/app/services/bucket/s3.py	44.73% <0.00%> (ø)

[frgfm]

@Nastaliss Would you mind adding a PR description and creating an issue referencing all the PRs on that topic please? :pray:

[Nastaliss]

issue