Update alpine image in Dockerfile

[adrianchiris]

alpine image has been pinned to 3.12 due to issues
that have already been resolved.

since sriov-network-device plugin image now properly builds
with latest alpine images, we can set it in Dockerfile.

As an additional benefit this will fix container image
related security vulnerabilities as new images are published.

Signed-off-by: Adrian Chiris [email protected]

[adrianchiris]

#407

[bn222]

\lgtm

[bn222]

Thanks for addressing the Github action.

\lgtm

[adrianchiris]

@SchSeba @zshi-redhat can we merge this ?

[bn222]

@adrianchiris I think we can mark all the reviews/comments as resolved. I think it is something only you can do?

[zshi-redhat]

image push to ppc64le and arm64 failed:

On arm64

#12 38.13 go: downloading golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1
#12 39.97 go: missing Git command. See https://golang.org/s/gogetcmd
#12 39.98 error obtaining VCS status: exec: "git": executable file not found in $PATH
#12 39.98 	Use -buildvcs=false to disable VCS stamping.
#12 39.98 make: *** [Makefile:72: /usr/src/sriov-network-device-plugin/build/sriovdp] Error 1
#12 ERROR: process "/bin/sh -c apk add --update --virtual build-dependencies build-base linux-headers make &&     cd /usr/src/sriov-network-device-plugin &&     make clean &&     make build" did not complete successfully: exit code: 2

On ppc64le

#12 49.66 error obtaining VCS status: exec: "git": executable file not found in $PATH
#12 49.66 	Use -buildvcs=false to disable VCS stamping.
#12 49.66 make: *** [Makefile:72: /usr/src/sriov-network-device-plugin/build/sriovdp] Error 1
#12 ERROR: process "/bin/sh -c apk add --update --virtual build-dependencies build-base linux-headers make &&     cd /usr/src/sriov-network-device-plugin &&     make clean &&     make build" did not complete successfully: exit code: 2

[bn222]

I think this might have to do with caches? We explicitly add git to avoid this error.