Add empty signature to block template

src/block_template.cpp

@@ -268,6 +268,10 @@ void BlockTemplate::update(const MinerData& data, const Mempool& mempool, Wallet
 
 	m_blockHeaderSize = m_blockHeader.size();
 
+	// Signature
+	uint8_t emptyByte = 0;
+	m_blockHeader.insert(m_blockHeader.end(), emptyByte, 64);
+
 	// Fill in m_txinGenHeight here so get_shares() can use it to calculate the correct PPLNS window
 	m_poolBlockTemplate->m_txinGenHeight = data.height;