Make mtxclient compile without nlohmann json implicit conversions

examples/crypto_bot.cpp

include/mtx/events_impl.hpp

include/mtx/responses/sync.hpp

include/mtxclient/http/client_impl.hpp

lib/crypto/client.cpp

lib/crypto/utils.cpp

lib/http/client.cpp

lib/structs/events/create.cpp

lib/structs/events/encrypted.cpp

lib/structs/events/messages/image.cpp

lib/structs/events/mscs/image_packs.cpp

lib/structs/events/presence.cpp

lib/structs/events/tombstone.cpp

lib/structs/pushrules.cpp

lib/structs/responses/common.cpp

lib/structs/responses/crypto.cpp

lib/structs/responses/groups.cpp

lib/structs/responses/members.cpp

lib/structs/responses/notifications.cpp

lib/structs/responses/sync.cpp