feat: pass fps dynamically

google-tests/test_helpers.h

@@ -27,7 +27,7 @@ std::vector<double> fetch_y_axis(npy::npy_data<double>& acc, int dim = 1);
 /** Returns the ssf_threshold as the filter output for debugging. */
 class DebugSsfStepDetectorThreshold : public SsfStepDetector {
 public:
-    DebugSsfStepDetectorThreshold(size_t len_refr);
+    DebugSsfStepDetectorThreshold(double fps);
     double filter(double val);
 };