Make SimHarness::CycleTime() const correct

Signed-off-by: Michael Richters <gedankenexperimenter@gmail.com>

testing/SimHarness.cpp

@@ -69,7 +69,7 @@ void SimHarness::SetCycleTime(uint8_t millis) {
   millis_per_cycle = millis;
 }
 
-uint8_t SimHarness::CycleTime() {
+uint8_t SimHarness::CycleTime() const {
   return millis_per_cycle;
 }
 

testing/SimHarness.h

@@ -35,7 +35,7 @@ class SimHarness {
   void Press(uint8_t row, uint8_t col);
   void Release(uint8_t row, uint8_t col);
   void SetCycleTime(uint8_t millis);
-  uint8_t CycleTime();
+  uint8_t CycleTime() const;
  private:
   uint8_t millis_per_cycle = 1;
 };