chore(vendor): bump micropython to 1.16

Relevant micropython commits:
  647fa63f9c457b616b1b20fdd98403b681302680 stm32/softtimer: Support static soft timer instances.

core/SConscript.firmware

@@ -203,6 +203,7 @@ SOURCE_MICROPYTHON = [
     'vendor/micropython/lib/utils/stdout_helpers.c',
     'vendor/micropython/ports/stm32/gccollect.c',
     'vendor/micropython/ports/stm32/pendsv.c',
+    'vendor/micropython/ports/stm32/softtimer.c',
     'vendor/micropython/py/argcheck.c',
     'vendor/micropython/py/asmarm.c',
     'vendor/micropython/py/asmbase.c',
@@ -276,6 +277,7 @@ SOURCE_MICROPYTHON = [
     'vendor/micropython/py/objtype.c',
     'vendor/micropython/py/objzip.c',
     'vendor/micropython/py/opmethods.c',
+    'vendor/micropython/py/pairheap.c',
     'vendor/micropython/py/parse.c',
     'vendor/micropython/py/parsenum.c',
     'vendor/micropython/py/parsenumbase.c',