fix misprint

app/api/routes/_blockchain.py

@@ -95,7 +95,7 @@ async def s_api_v1_blockchain_send_new_content_message(request):
         return response.json({
             'address': platform.address.to_string(1, 1, 1),
             'amount': str(int(0.15 * 10 ** 9)),
-            'payload': b64encode(
+            'payload': (
                 begin_cell()
                     .store_uint(0x5491d08c, 32)
                     .store_uint(int.from_bytes(encrypted_content_cid.content_hash, "big", signed=False), 256)