Fix spacing in gcode.cpp

Followup to #6940

Marlin/gcode.cpp

@@ -184,7 +184,7 @@ void GCodeParser::parse(char *p) {
 
     if (PARAM_TEST) {
 
-      while (*p == ' ') p++;                    // skip spaces vetween parameters & values
+      while (*p == ' ') p++;                    // Skip spaces between parameters & values
       const bool has_num = DECIMAL_SIGNED(*p);  // The parameter has a number [-+0-9.]
 
       #if ENABLED(DEBUG_GCODE_PARSER)