Check the reason is "Not Acceptable" for doing fallback from client group chat...

Check the reason is "Not Acceptable" for doing fallback from client group chat room to basic chat room.

src/chat/chat-room/client-group-to-basic-chat-room.cpp

@@ -21,6 +21,7 @@
 #include "client-group-to-basic-chat-room.h"
 #include "proxy-chat-room-p.h"
 #include "c-wrapper/c-wrapper.h"
+#include "conference/session/call-session.h"
 #include "core/core-p.h"
 
 // =============================================================================
@@ -61,7 +62,7 @@ public:
 		if (!cgcr)
 			return;
 		if ((newState == LinphoneCallError) && (cgcr->getState() == ChatRoom::State::CreationPending)
-			&& (invitedAddresses.size() == 1)) {
+			&& (session->getReason() == LinphoneReasonNotAcceptable) && (invitedAddresses.size() == 1)) {
 			cgcr->getPrivate()->onCallSessionStateChanged(session, newState, message);
 			cgcr->getPrivate()->setCallSessionListener(nullptr);
 			cgcr->getPrivate()->setChatRoomListener(nullptr);