feat: pin devbox image (#19) #28

Job	Run time
Check Signed Tag	7s
Build Release Binaries (20.04, windows/amd64)	2m 52s
Build Release Binaries (20.04, linux/amd64)	6m 11s
Build Release Binaries (20.04, linux/ppc64le)	5m 46s
Build Release Binaries (20.04, linux/arm64)	6m 13s
Build Release Binaries (20.04, linux/riscv64)	6m 6s
Build Release Binaries (20.04, linux/s390x)	6m 6s
Create containerd Release	28s
	33m 49s

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