ci: retry on network errors
ci: retry on network errors

Seen today in https://github.com/rook/rook/pull/8272/checks?check_run_id=3010477951

```
github.com/rook/rook/pkg/apis/ceph.rook.io/v1 imports
	github.com/hashicorp/vault/api: github.com/hashicorp/vault@v1.4.2: reading https://proxy.golang.org/github.com/hashicorp/vault/@v/v1.4.2.zip: 503 Service Unavailable
	server response: Service Unavailable
github.com/rook/rook/pkg/daemon/ceph/osd/kms imports
	github.com/libopenstorage/secrets/vault imports
	github.com/hashicorp/vault/command/agent/auth: github.com/hashicorp/vault@v1.4.2: reading https://proxy.golang.org/github.com/hashicorp/vault/@v/v1.4.2.zip: 503 Service Unavailable
	server response: Service Unavailable
github.com/rook/rook/pkg/daemon/ceph/osd/kms imports
	github.com/libopenstorage/secrets/vault imports
	github.com/hashicorp/vault/command/agent/auth/kubernetes: github.com/hashicorp/vault@v1.4.2: reading https://proxy.golang.org/github.com/hashicorp/vault/@v/v1.4.2.zip: 503 Service Unavailable
	server response: Service Unavailable
make: *** [go.mod.check] Error 1
```

Also https://github.com/rook/rook/pull/8272/checks?check_run_id=3010482113

```
go get: sigs.k8s.io/controller-tools@v0.4.1 updating to
	sigs.k8s.io/controller-tools@v0.5.1-0.20210420220833-f284e2e8098c requires
	k8s.io/apimachinery@v0.20.2 requires
	github.com/json-iterator/go@v1.1.10: verifying go.mod: github.com/json-iterator/go@v1.1.10/go.mod: reading https://sum.golang.org/tile/8/0/x005/043: stream error: stream ID 1099; INTERNAL_ERROR
make[3]: *** [/home/runner/work/rook/rook/.cache/tools/linux_amd64/controller-gen-f284e2e8098cb0193c2b0c7c1c651ae75496539b] Error 1
make[2]: *** [generate-csv-ceph-templates] Error 1
```

Signed-off-by: Sébastien Han <62d754cc350e84d3b1c32ae79f976f5348e74a40@redhat.com>

rook/nfs,rook/rook,rook/nfs,rook/rook,rook/rook,rook/nfs,rook/rook,rook/rook