chore: fix lint errors reported by golangci-lint

[chetan-rns]

Fix the lint errors reported when running make lint locally.

Checklist:

• Either (a) I've created an enhancement proposal and discussed it with the community, (b) this is a bug fix, or (c) this is a chore.
• The title of the PR is (a) conventional with a list of types and scopes found here, (b) states what changed, and (c) suffixes the related issues number. E.g. "fix(controller): Updates such and such. Fixes #1234".
• I've signed my commits with DCO
• I have written unit and/or e2e tests for my change. PRs without these are unlikely to be merged.
• My builds are green. Try syncing with master if they are not.
• My organization is added to USERS.md.

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
6.3% Duplication on New Code

See analysis details on SonarCloud

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.81%. Comparing base (8405f2e) to head (8c1152c).
Report is 50 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3458      +/-   ##
==========================================
+ Coverage   81.83%   82.81%   +0.97%     
==========================================
  Files         135      135              
  Lines       20688    16998    -3690     
==========================================
- Hits        16931    14077    -2854     
+ Misses       2883     2034     -849     
- Partials      874      887      +13     

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[github-actions]

Go Published Test Results

2 142 tests   2 142 ✅  2m 51s ⏱️
  119 suites      0 💤
    1 files        0 ❌

Results for commit 8c1152c.

[github-actions]

E2E Tests Published Test Results

  4 files    4 suites   3h 43m 27s ⏱️
108 tests  98 ✅  6 💤  4 ❌
446 runs  408 ✅ 24 💤 14 ❌

For more details on these failures, see this check.

Results for commit 8c1152c.

[jgwest]

LGTM, tests are passing, and appends with no variadic function args are going to be a no-op.

[zachaller]

This does not change the cli version: https://github.com/argoproj/argo-rollouts/blob/master/Dockerfile#L15 this will be bumped in a different PR