fix(core): remove unused variables

Author: GuillaumeLagrange

core/src/walltime.cpp

@@ -18,9 +18,6 @@
 
 namespace codspeed {
 
-const double IQR_OUTLIER_FACTOR = 1.5;
-const double STDEV_OUTLIER_FACTOR = 3.0;
-
 // Times are per iteration
 struct BenchmarkStats {
   double min_ns;