style: replace deprecated linters with new ones (backport #361)

[mergify]

Description

closes: #XXXX

• maligned -> govet
• varcheck, structcheck, deadcode -> unused
• golint -> revive
• scopelint -> exportloopref

Motivation and context

How has this been tested?

Screenshots (if appropriate):

Checklist:

• I followed the contributing guidelines and code of conduct.
• I have added a relevant changelog to CHANGELOG.md
• I have added tests to cover my changes.
• I have updated the documentation accordingly.

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This is an automatic backport of pull request #361 done by [Mergify](https://mergify.com).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

❗ No coverage uploaded for pull request base (release/v4.0.x@2555d67). Click here to learn what that means.

Additional details and impacted files

@@                Coverage Diff                @@
##             release/v4.0.x     #363   +/-   ##
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  Coverage                  ?   50.28%           
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  Files                     ?       10           
  Lines                     ?     1406           
  Branches                  ?        0           
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  Hits                      ?      707           
  Misses                    ?      654           
  Partials                  ?       45