cmd/govulncheck: skip TestCommand in short mode

Short tests aren't expected to access the internet, even if it happens
to be just proxy.golang.org. Caught by the new no-network check in LUCI.

Change-Id: I233158cdda99eca011390d1375310fde82eedb19
Reviewed-on: https://go-review.googlesource.com/c/vuln/+/510676
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Heschi Kreinick <heschi@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Run-TryBot: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

cmd/govulncheck/main_command_118_test.go

@@ -103,6 +103,10 @@ func init() {
 }
 
 func TestCommand(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping test that uses internet in short mode")
+	}
+
 	testDir, err := os.Getwd()
 	if err != nil {
 		t.Fatal(err)