queen-attack: Ensure test versioning consistency with other exercises (…

…#577)

* Errorf -> Fatalf

See #470

exercises/queen-attack/queen_attack_test.go

@@ -33,7 +33,7 @@ var tests = []struct {
 
 func TestTestVersion(t *testing.T) {
 	if testVersion != targetTestVersion {
-		t.Errorf("Found testVersion = %v, want %v.", testVersion, targetTestVersion)
+		t.Fatalf("Found testVersion = %v, want %v.", testVersion, targetTestVersion)
 	}
 }