Increase bed heater timeout to 20min

Firmware/variants/1_75mm_MK3S-EINSy10a-E3Dv6full.h

@@ -416,7 +416,7 @@
 
 // temperature runaway
 #define TEMP_RUNAWAY_BED_HYSTERESIS 15
-#define TEMP_RUNAWAY_BED_TIMEOUT 360
+#define TEMP_RUNAWAY_BED_TIMEOUT 1200
 
 #define TEMP_RUNAWAY_EXTRUDER_HYSTERESIS 15
 #define TEMP_RUNAWAY_EXTRUDER_TIMEOUT 45