test: io: update to use new object system

io-test/mkdir.c

@@ -1,4 +1,5 @@
 #include <blue/io/directory.h>
+#include <blue/io/path.h>
 
 int main(int argc, const char **argv)
 {
@@ -16,6 +17,6 @@ int main(int argc, const char **argv)
 		return -1;
 	}
 
-	b_directory_release(dir);
+	b_directory_unref(dir);
 	return 0;
 }