[release-1.20] Bump cert-manager to v1.18.1

[k8s-infra-cherrypick-robot]

This is an automated cherry-pick of #5711

/assign mboersma

NONE

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 52.84%. Comparing base (fa45b4a) to head (a158e47).
Report is 7 commits behind head on release-1.20.

Additional details and impacted files

@@              Coverage Diff              @@
##           release-1.20    #5722   +/-   ##
=============================================
  Coverage         52.84%   52.84%           
=============================================
  Files               278      278           
  Lines             29610    29610           
=============================================
  Hits              15647    15647           
  Misses            13146    13146           
  Partials            817      817           

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[mboersma]

/retest

[mboersma]

/lgtm
/approve

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 28cc233bbed825dcac86bd911b43ad3ce0ce2755

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: mboersma

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