Fix build on macOS Big Sur

This hopefully adds the correct include directive for the UVC_GetAttribute function. Tested on macOS 11.1, PureThermal Mini and Lepton 3.5.

The error messages were:

../lepton_sdk/Src/LEPTON_SDK.c:142:18: error: implicit declaration of function 'UVC_GetAttribute' is invalid in C99
      [-Werror,-Wimplicit-function-declaration]
        result = UVC_GetAttribute(portDescPtr, commandID, attributePtr, attributeWordLength);
                 ^
../lepton_sdk/Src/LEPTON_SDK.c:142:18: note: did you mean 'LEP_GetAttribute'?
../lepton_sdk/Src/LEPTON_SDK.c:102:12: note: 'LEP_GetAttribute' declared here
LEP_RESULT LEP_GetAttribute(LEP_CAMERA_PORT_DESC_T_PTR portDescPtr,
           ^
../lepton_sdk/Src/LEPTON_SDK.c:188:18: error: implicit declaration of function 'UVC_SetAttribute' is invalid in C99
      [-Werror,-Wimplicit-function-declaration]
        result = UVC_SetAttribute(portDescPtr, commandID, attributePtr, attributeWordLength);
                 ^
../lepton_sdk/Src/LEPTON_SDK.c:188:18: note: did you mean 'LEP_SetAttribute'?
../lepton_sdk/Src/LEPTON_SDK.c:155:12: note: 'LEP_SetAttribute' declared here
LEP_RESULT LEP_SetAttribute(LEP_CAMERA_PORT_DESC_T_PTR portDescPtr,
           ^
../lepton_sdk/Src/LEPTON_SDK.c:227:18: error: implicit declaration of function 'UVC_RunCommand' is invalid in C99
      [-Werror,-Wimplicit-function-declaration]
        result = UVC_RunCommand(portDescPtr, commandID);
                 ^
../lepton_sdk/Src/LEPTON_SDK.c:227:18: note: did you mean 'LEP_RunCommand'?
../lepton_sdk/Src/LEPTON_SDK.c:196:12: note: 'LEP_RunCommand' declared here

groupgets / GetThermal

Fix build on macOS Big Sur #39