fru_reader: add header for off_t

GCC-14 with the latest Yocto refresh give the following compile
failure:

```
| ../git/src/fru_reader.hpp:36:27: error: 'off_t' was not declared in this scope
|    36 |     std::function<int64_t(off_t offset, size_t len, uint8_t* outbuf)>;
```

This appears to be defined in `stdio.h`, so include `<cstdio>`.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I4dadec5f0735a902d6fd47de6667ebc5cd670e15
diff --git a/src/fru_reader.hpp b/src/fru_reader.hpp
index f54d900..4083be1 100644
--- a/src/fru_reader.hpp
+++ b/src/fru_reader.hpp
@@ -17,6 +17,7 @@
 #pragma once
 
 #include <cstdint>
+#include <cstdio>
 #include <functional>
 #include <map>
 #include <optional>
diff --git a/src/fru_utils.hpp b/src/fru_utils.hpp
index f6552a5..12e28b1 100644
--- a/src/fru_utils.hpp
+++ b/src/fru_utils.hpp
@@ -22,6 +22,7 @@
 #include <sdbusplus/asio/object_server.hpp>
 
 #include <cstdint>
+#include <cstdio>
 #include <functional>
 #include <regex>
 #include <string>