When running the test on `arduino-mega2560` printing the float failed
and was printed as ` ?`.
Calculated ? bits of entropy from 10000 samples.
Replace using `printf` floating point printing by using `fmt/print_float`.
Now the test succeeds on `arduino-mega2560`.
As `print_float` does not buffer and is used with `printf` the output
should be flushed before calling it if `fflush` is available.
cpp check is reporting the following error
error (shiftTooManyBitsSigned):
Shifting signed 32-bit value by 31 bits is undefined behaviour
Fix by ensuring the `1` is an `uint32_t` before shifting.
