update cosign to the latest v1 release, v1.13.6 (#5095) #2471

Job	Run time
kurl-addon-changes-filter	7s
generate-tag	4s
build-kurl-proxy-melange-packages (ubuntu-20.04, amd64)	1m 40s
build-kurl-proxy-melange-packages (arm64-runner-set, arm64)	2m 17s
build-web	3m 26s
build-migrations-melange-packages (ubuntu-20.04, amd64)	1m 19s
build-kotsadm-melange-packages (ubuntu-20.04, amd64)	7m 30s
build-migrations-melange-packages (arm64-runner-set, arm64)	2m 1s
build-kotsadm-melange-packages (arm64-runner-set, arm64)	6m 30s
generate-kots-release-notes-pr	4s
Run regression testing	0s
build-migrations	35s
build-kurl-proxy	47s
goreleaser	10m 26s
build-kots	2m 29s
build-kotsadm	48s
build-kotsadm-bundle	2m 0s
generate-kurl-addon	2m 13s
publish-kurl-addon	7s
validate-kurl-addon	16s
regression-test	0s
publish-pact-contracts	27s
build-airgap	2m 35s
	47m 41s

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