Fixing build on Ubuntu 24.04 w/ Clang 20 (#936)

Some compiler implementations seem to be very adamant that
`std::unique_ptr` lives in `<memory>` and without this change I was
unable to build.

tools/imageio/imageio.h

@@ -37,6 +37,7 @@
 #include <string>
 #include <sstream>
 #include <vector>
+#include <memory>
 
 #include <fmt/format.h>
 #include <math.h>