test: avoid non-constant format string in printf

In preparation to the next commit which will bump the golang version we
want to avoid calling printf with non-constant format strings. This
needs to be done as the govet will include a new rule that prohibits
exactly that -- calling into printf with non-constant format strings.

Author: GeorgeTsagk

internal/test/copy.go

@@ -237,7 +237,7 @@ func checkAliasing(t *testing.T, debug, strict bool, f1, f2 reflect.Value,
 				"(shared %s)", path, f1.Kind())
 
 			if strict {
-				t.Fatalf(msg)
+				t.Fatal(msg)
 			}
 
 			if debug {