ports/stm: drop stale audioio sample_rate pot entry

Removed leftover msgid "sample_rate must be > 0" from
locale/circuitpython.pot. The raise was replaced with
mp_arg_validate_int_min in d42941d but the pot entry
was not regenerated.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: Chris Nourse

locale/circuitpython.pot

@@ -4166,10 +4166,6 @@ msgstr ""
 msgid "rsplit(None,n)"
 msgstr ""
 
-#: ports/stm/common-hal/audioio/AudioOut.c
-msgid "sample_rate must be > 0"
-msgstr ""
-
 #: shared-bindings/audiofreeverb/Freeverb.c
 msgid "samples_signed must be true"
 msgstr ""