fix: remove outdated ioutil package dependencies

[fengshunli]

Signed-off-by: fengshunli 1171313930@qq.com

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]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
14.0% Duplication

[codecov]

Codecov Report

Base: 81.60% // Head: 81.60% // No change to project coverage 👍

Coverage data is based on head (7d969ef) compared to base (d7df8b3).
Patch coverage: 91.66% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2583   +/-   ##
=======================================
  Coverage   81.60%   81.60%           
=======================================
  Files         130      130           
  Lines       19483    19483           
=======================================
  Hits        15900    15900           
  Misses       2766     2766           
  Partials      817      817           

Impacted Files	Coverage Δ
utils/defaults/defaults.go	89.37% <0.00%> (ø)
metricproviders/datadog/datadog.go	77.93% <100.00%> (ø)
metricproviders/graphite/api.go	78.04% <100.00%> (ø)
metricproviders/kayenta/kayenta.go	84.47% <100.00%> (ø)
metricproviders/webmetric/webmetric.go	68.88% <100.00%> (ø)
pkg/kubectl-argo-rollouts/cmd/create/create.go	64.96% <100.00%> (ø)
pkg/kubectl-argo-rollouts/cmd/lint/lint.go	85.84% <100.00%> (ø)

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[github-actions]

Go Published Test Results

1 850 tests   1 850 ✔️  2m 32s ⏱️
   112 suites         0 💤
       1 files           0 ❌

Results for commit 7d969ef.

[github-actions]

E2E Tests Published Test Results

    2 files      2 suites   1h 40m 8s ⏱️
  96 tests   89 ✔️ 3 💤 4 ❌
198 runs  186 ✔️ 6 💤 6 ❌

For more details on these failures, see this check.

Results for commit 7d969ef.