BUILD: fix yamllint complaints #510

Job	Run time
generate-specification	46s
HAProxy check commit message	0s
generate-models	1m 3s
golangci-lint	54s
license-check	21s
Build	29s
lint-spec	7s
go mod tidy	21s
Tests	2m 42s
e2e on HAProxy (2.1)	41s
e2e on HAProxy (2.2)	42s
e2e on HAProxy (2.3)	41s
e2e on HAProxy (2.4)	41s
e2e on HAProxy (2.5)	40s
e2e on HAProxy (2.6)	44s
e2e on HAProxy (2.7)	41s
e2e on HAProxy (2.8)	41s
	12m 14s

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