checker: fix typo on error message and related test

vlib/v/checker/checker.v

@@ -1401,7 +1401,7 @@ fn (mut c Checker) stmt(node ast.Stmt) {
 			if it.is_method {
 				sym := c.table.get_type_symbol(it.receiver.typ)
 				if sym.kind == .interface_ {
-					c.error('interaces cannot be used as method receiver', it.receiver_pos)
+					c.error('interfaces cannot be used as method receiver', it.receiver_pos)
 				}
 				// if sym.has_method(it.name) {
 				// c.warn('duplicate method `$it.name`', it.pos)

vlib/v/checker/tests/no_interface_receiver.out

@@ -1,4 +1,4 @@
-vlib/v/checker/tests/no_interface_receiver.v:5:5: error: interaces cannot be used as method receiver
+vlib/v/checker/tests/no_interface_receiver.v:5:5: error: interfaces cannot be used as method receiver
     3 | }
     4 |
     5 | fn (a Animal) str() {}