Fix stray backtick at end of lightshow_format.h

Markdown artifact caused a compile error: stray '`' in program.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

arduino/cosplay_lights/lightshow_format.h

@@ -48,5 +48,4 @@ inline ShowDef read_show_def(const ShowDef* ptr) {
     sd.length = pgm_read_word(&ptr->length);
     sd.mode   = pgm_read_byte(&ptr->mode);
     return sd;
-}
-`
+}