chore: bump coredns to v1.6.6

[CecileRobertMichon]

Reason for Change:

coredns/coredns#3547

Issue Fixed:

#2553

Requirements:

• uses conventional commit messages
• includes documentation
• adds unit tests
• tested upgrade from previous version

Notes:

[marosset]

/lgtm

[codecov]

Codecov Report

Merging #2555 into master will decrease coverage by 0.61%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2555      +/-   ##
==========================================
- Coverage   72.73%   72.12%   -0.62%     
==========================================
  Files         130      130              
  Lines       24043    24468     +425     
==========================================
+ Hits        17488    17647     +159     
- Misses       5532     5799     +267     
+ Partials     1023     1022       -1

[jackfrancis]

/lgtm

[acs-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: CecileRobertMichon, jackfrancis, marosset

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