fix build under Fedora 38

Building brlaser under Fedora 38 gives the following error in
test/tempfile.h:
error: 'uint8_t' was not declared in this scope

This commit fixes it by explicitly including `cstdin` in the file, so
`uint8_t` is correctly defined there.

test/tempfile.h

@@ -21,6 +21,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <cstdint>
 #include <vector>
 
 class tempfile {