fix versioning bug

src/p2pool.cpp

@@ -994,7 +994,7 @@ void p2pool::parse_get_version_rpc(const char* data, size_t size)
 
 	constexpr uint64_t major = 3;
 	constexpr uint64_t minor = 11;
-	constexpr uint64_t required = (major << 20) | minor;
+	constexpr uint64_t required = (major << 16) | minor;
 
 	if (version < required) {
 		const uint64_t version_hi = version >> 16;