[BUG] problem using sscanf with platform ststm32

[rubienr]

Description
Set time command fails to parse on ststm32 platform.

How to reproduce

• pio test -e ststm32 -f easycomm2_ao_lo_op_ip_an_st_ve

test/easycomm2_ao_lo_op_ip_an_st_ve/test.cpp:254:test_parse_acquisition_of_signal	[PASSED]
test/easycomm2_ao_lo_op_ip_an_st_ve/test.cpp:255:test_parse_loss_of_signal	[PASSED]
test/easycomm2_ao_lo_op_ip_an_st_ve/test.cpp:256:test_parse_set_output_01	[PASSED]
test/easycomm2_ao_lo_op_ip_an_st_ve/test.cpp:257:test_parse_set_output_02	[PASSED]
test/easycomm2_ao_lo_op_ip_an_st_ve/test.cpp:258:test_parse_read_input_01	[PASSED]
test/easycomm2_ao_lo_op_ip_an_st_ve/test.cpp:259:test_parse_read_input_02	[PASSED]
test/easycomm2_ao_lo_op_ip_an_st_ve/test.cpp:260:test_parse_read_analogue_input_01	[PASSED]
test/easycomm2_ao_lo_op_ip_an_st_ve/test.cpp:261:test_parse_read_analogue_input_02	[PASSED]
test/easycomm2_ao_lo_op_ip_an_st_ve/test.cpp:53:test_parse_set_time_01:FAIL: failed to parse	[FAILED]
test/easycomm2_ao_lo_op_ip_an_st_ve/test.cpp:53:test_parse_set_time_02:FAIL: failed to parse	[FAILED]
test/easycomm2_ao_lo_op_ip_an_st_ve/test.cpp:53:test_parse_set_time_03:FAIL: failed to parse	[FAILED]
test/easycomm2_ao_lo_op_ip_an_st_ve/test.cpp:265:test_parse_request_version	[PASSED]

Expected behaviour
All tests green.

[rubienr]

The ststm32 code links against newlib-nano which comes with limited support and doesn't implement all length modifiers in printf and scanf. To link against full lib (disable newlib-nano) remove the --specs=noano.specs by defining
-D PIO_FRAMEWORK_ARDUINO_STANDARD_LIB build_flags.

Recommende solution at Stackoverflow: Problem with using scanf function under stm32

Relates to:

1. https://stackoverflow.com/questions/58836403/problem-with-using-scanf-function-under-stm32
2. https://community.platformio.org/t/strange-sscanf-behavior-mbed-stm32f446/12658