Change include guards in quantum/ to pragma once (#11239)

quantum/process_keycode/process_leader.h

@@ -14,8 +14,7 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef PROCESS_LEADER_H
-#define PROCESS_LEADER_H
+#pragma once
 
 #include "quantum.h"
 
@@ -37,5 +36,3 @@ void qk_leader_start(void);
     extern uint16_t leader_sequence[5]; \
     extern uint8_t  leader_sequence_size
 #define LEADER_DICTIONARY() if (leading && timer_elapsed(leader_time) > LEADER_TIMEOUT)
-
-#endif