🐛 Fix open for bin rename (#23351)

buildroot/share/PlatformIO/scripts/marlin.py

 	# If FIRMWARE_BIN is defined by config, override all
 	import re
 	patt = re.compile("^\\s*#define\\s+FIRMWARE_BIN\\s+\"?(.+)\"?")
-	with open(join("Marlin", "Configuration.h")) as f:
+	with open(join("Marlin", "Configuration.h"), encoding="utf-8") as f:
 		for line in f:
 			m = patt.search(line)
 			if m != None: