fix: add missing header files (#257)

my gcc version:

```text
gcc 版本 13.2.1 20230801 (GCC)
```

build log:
```log
[ 69%] Building CXX object src/observer/CMakeFiles/observer_static.dir/storage/trx/trx.cpp.o
In file included from /home/yunshu/Studio/GitHub/miniob/src/observer/storage/persist/persist.cpp:18:
/home/yunshu/Studio/GitHub/miniob/src/observer/storage/persist/persist.h:48:15: 错误：‘uint64_t’未声明
   48 |   RC write_at(uint64_t offset, int size, const char *data, int64_t *out_size = nullptr);
      |               ^~~~~~~~
```

### What problem were solved in this pull request?

Problem: build failed because the declaration of uint64_t could not be
found.

### What is changed and how it works?

add `<stdint.h>`

src/observer/storage/persist/persist.h

@@ -16,6 +16,7 @@ See the Mulan PSL v2 for more details. */
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>