Remove io/ioutil since is deprecated

[umbynos]

Please check if the PR fulfills these requirements

• The PR has no duplicates (please search among the Pull Requests
  before creating one)
• Tests for the changes have been added (for bug fixes / features)

• What kind of change does this PR introduce?

remove deprecated package

• What is the current behavior?

Deprecated: As of Go 1.16, the same functionality is now provided by package io or package os, and those implementations should be preferred in new code. See the specific function documentation for details.

• What is the new behavior?

We use package io or os

• Does this PR introduce a breaking change?

no

• Other information:

[codecov-commenter]

Codecov Report

Patch coverage: 42.10% and no project coverage change.

Comparison is base (6c5dfae) 10.83% compared to head (bf55f11) 10.83%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #818   +/-   ##
=======================================
  Coverage   10.83%   10.83%           
=======================================
  Files          52       52           
  Lines        4043     4043           
=======================================
  Hits          438      438           
  Misses       3550     3550           
  Partials       55       55           

Flag	Coverage Δ
unit	10.83% <42.10%> (ø)

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

Files Changed	Coverage Δ
conn.go	0.00% <0.00%> (ø)
tools/download.go	30.62% <0.00%> (ø)
tools/tools.go	0.00% <0.00%> (ø)
upload/upload.go	41.15% <0.00%> (ø)
utilities/utilities.go	11.49% <100.00%> (ø)
v2/pkgs/indexes.go	61.29% <100.00%> (ø)
v2/pkgs/tools.go	70.34% <100.00%> (ø)

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.