Upgraded alpine base image

[Rajan-226]

What type of PR is this?
/kind cleanup

What this PR does / why we need it:

Which issue(s) this PR fixes:
Fixes #3936

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

The base image `alpine` now has been promoted from `alpine:3.18.2` to `alpine:3.18.3`.

[karmada-bot]

Welcome @Rajan-226! It looks like this is your first PR to karmada-io/karmada 🎉

[RainbowMango]

Thanks @Rajan-226 , looks all good. You might need to sign the commit as per:
https://github.com/karmada-io/karmada/pull/3942/checks?check_run_id=15886826982.

[codecov-commenter]

Codecov Report

Merging #3942 (f496308) into master (25db1e0) will decrease coverage by 0.02%.
The diff coverage is n/a.

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@@            Coverage Diff             @@
##           master    #3942      +/-   ##
==========================================
- Coverage   54.71%   54.69%   -0.02%     
==========================================
  Files         229      229              
  Lines       22074    22074              
==========================================
- Hits        12077    12074       -3     
- Misses       9351     9354       +3     
  Partials      646      646              

Flag	Coverage Δ
unittests	54.69% <ø> (-0.02%)	⬇️

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

see 1 file with indirect coverage changes

[Rajan-226]

@RainbowMango Done

[RainbowMango]

/lgtm
/approve

Thanks @Rajan-226 and welcome to Karmada~

[karmada-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: RainbowMango

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