Increased memory buffer size to 10K

Since EIP-712 memory usage has increased

src/mem.c

@@ -11,7 +11,7 @@
 #include <stdint.h>
 #include "mem.h"
 
-#define SIZE_MEM_BUFFER 8192
+#define SIZE_MEM_BUFFER 10240
 
 static uint8_t mem_buffer[SIZE_MEM_BUFFER];
 static size_t mem_idx;