signed-unsigned comparison is always false

[ku3i]

local variable m is of unsigned type:

Adafruit_FreeTouch.cpp: In member function 'uint16_t Adafruit_FreeTouch::measure()':
Adafruit_FreeTouch.cpp:111:9: warning: comparison is always false due to limited range of data type [-Wtype-limits]
if (m == -1)

https://github.com/adafruit/Adafruit_FreeTouch/blob/cf2f2f6d5916aa208628b531ef369effb3950478/Adafruit_FreeTouch.cpp#L111C3-L111C15