Fix Botan 2/3 include

Botan::secure_scrub_memory -> defined in mem_ops.h
Botan::secure_vector -> defined in secmem.h

The reason only including secmem.h worked in previous (<3.0) versions of
Botan was because secmem.h included mem_ops.h. This is no longer the
case since commit
randombit/botan@49dbbcb (2023-10-11;
"Split out allocator helpers to allocator.h")

Fixes #10038

src/keys/FileKey.h

@@ -19,6 +19,7 @@
 #ifndef KEEPASSX_FILEKEY_H
 #define KEEPASSX_FILEKEY_H
 
+#include <botan/mem_ops.h>
 #include <botan/secmem.h>
 
 #include "keys/Key.h"