FIX(client,server): Packets of exactly max size were rejected

Due to an off-by-one error in the comparison logic, packets that are
exactly the maximum allowed size were rejected. This is now fixed.

src/MumbleProtocol.cpp

@@ -300,7 +300,7 @@ namespace Protocol {
 
 	std::size_t writeSnippet(std::span< const byte > source, std::vector< byte > &destination, std::size_t offset,
 							 std::size_t maxPacketSize) {
-		if (maxPacketSize <= offset + source.size()) {
+		if (maxPacketSize < offset + source.size()) {
 			qWarning("MumbleProtocol: Buffer overflow while writing snippet. Max buffer size is %zu and required size "
 					 "is %zu",
 					 maxPacketSize, offset + source.size());