chore(docker): update confluentinc/cp-kafka docker tag to v8

[renovate]

This PR contains the following updates:

Package	Update	Change
confluentinc/cp-kafka	major	7.9.7 → 8.3.0

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 60.31%. Comparing base (027b9ba) to head (8b323af).

❗ There is a different number of reports uploaded between BASE (027b9ba) and HEAD (8b323af). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (027b9ba)	HEAD (8b323af)
	6	5

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1869       +/-   ##
===========================================
- Coverage   93.28%   60.31%   -32.98%     
===========================================
  Files         295      295               
  Lines        4679     4679               
  Branches      873      873               
===========================================
- Hits         4365     2822     -1543     
- Misses        314     1857     +1543     

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