Fix compilation without implicit nlohmann conversions

CMakeLists.txt

io.github.NhekoReborn.Nheko.yaml

src/Cache.cpp

src/ChatPage.cpp

src/Logging.h

src/encryption/DeviceVerificationFlow.cpp

src/encryption/Olm.cpp

src/timeline/TimelineModel.h

src/ui/UIA.cpp

src/ui/UIA.h