chore: specify the K8S cluster version used for the test

[tao12345666333]

Signed-off-by: Jintao Zhang zhangjintao9020@gmail.com

Type of change:

• CI

What this PR does / why we need it:

Specify the K8S cluster version used for the test. To avoid CI failure due to inconsistent local environment version.

[codecov-commenter]

Codecov Report

Merging #797 (c1fbfbd) into master (d4c5b09) will increase coverage by 0.05%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #797      +/-   ##
==========================================
+ Coverage   33.09%   33.15%   +0.05%     
==========================================
  Files          67       68       +1     
  Lines        7127     7143      +16     
==========================================
+ Hits         2359     2368       +9     
- Misses       4499     4505       +6     
- Partials      269      270       +1     

Impacted Files	Coverage Δ
pkg/api/router/router.go	72.72% <0.00%> (-2.28%)	⬇️
pkg/ingress/controller.go	1.00% <0.00%> (-0.01%)	⬇️
pkg/api/router/apisix_healthz.go	66.66% <0.00%> (ø)
pkg/api/server.go	82.27% <0.00%> (+0.46%)	⬆️

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[gxthrj]

e2e failed. Re-runed.

[tao12345666333]

It's green! Merged.