test/network.bats: s/which/command -v/
test/network.bats: s/which/command -v/

This fixes the following shellcheck warning:

In test/network.bats line 118:
	cp "$(which conmon)" "$CONMON_BINARY"
              ^---^ SC2230: which is non-standard. Use builtin 'command -v' instead.

Signed-off-by: Kir Kolyshkin <3a017b8ddb3f9cf3e4a59978b004111bdeb97f08@gmail.com>

kubernetes-incubator/ocid,nalind/cri-o,kubernetes-incubator/ocid,kubernetes-incubator/cri-o,kubernetes-incubator/cri-o,kubernetes-incubator/cri-o,kubernetes-incubator/cri-o,nalind/cri-o,kubernetes-incubator/ocid,nalind/cri-o