Bump chainguard-dev/cosign from 0.0.6 to 0.0.9 in /tflib/publisher #64

Job	Run time
presubmit-matrix	4s
presubmit-build (alpine-base)	31s
presubmit-build (apko, configs/latest.melange.yaml)	29m 13s
presubmit-build (gcc-musl)	1m 12s
presubmit-build (melange, configs/latest.melange.yaml)	29m 50s
presubmit-build (musl-dynamic)	34s
presubmit-build (sdk, configs/latest.melange.yaml)	1h 4m 18s
presubmit-build (wolfictl, configs/latest.melange.yaml)	53m 29s
presubmit-roundup	2s
	2h 59m 13s

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