Upgrade cosign to support other platforms (#1741)
Upgrade cosign to support other platforms (#1741)

Now the Cosign 1.3.0 supports both amd64 and arm64
platform now, so just upgrade cosign to this version
to support installation on both platforms.

Signed-off-by: trevor.tao <215a608758adc496e5994cb6a15aef6c78b0b040@arm.com>
istio/tools,istio/tools,istio/tools,istio/tools,istio/tools,istio/tools