compiler: unsigned number properly printed and converted to string

fix: array accessing now works with unsigned numbers

compiler/parser.v

@@ -1962,7 +1962,8 @@ fn (p mut Parser) index_expr(typ_ string, fn_ph int) string {
 		// expression inside [ ]
 		if is_arr {
 			T := p.table.find_type(p.expression())
-			if T.parent != 'int' {
+			// Allows only i8-64 and u8-64 to be used when accessing an array
+			if T.parent != 'int' && T.parent != 'u32' {
 				p.check_types(T.name, 'int')
 			}
 		}