Update upload-artifact action to v4

[creydr]

Fixes

Error: This request has been automatically failed because it uses a deprecated version of `actions/upload-artifact: v2`. Learn more: https://github.blog/changelog/2024-02-13-deprecation-notice-v1-and-v2-of-the-artifact-actions/

e.g in https://github.com/knative-extensions/eventing-kafka-broker/actions/runs/12588648354/job/35086964011

[pierDipi]

/lgtm
/approve

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: creydr, pierDipi

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 45.44%. Comparing base (d90c382) to head (2f564e6).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4209      +/-   ##
==========================================
- Coverage   45.50%   45.44%   -0.07%     
==========================================
  Files         270      270              
  Lines       19873    19893      +20     
==========================================
- Hits         9044     9041       -3     
- Misses      10111    10133      +22     
- Partials      718      719       +1     

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[creydr]

/retest-required

[pierDipi]

/retest-required

[creydr]

/test reconciler-tests