Narrow scope follows in gcc unused warning

Declaration of SCL and SDA in lines 134, 135 and 148, 149 to int limited the scope of variables and follows in unused-variable warning under Arduino 1.8.19.

Solution: Make the declaration in scope of setup function, e.g. before the pin definition block around line 121.

Not really a bug, but wondering why the DebugPrintln(3, SCL); line works.