Fix SearchBase parameter (#328)

The class "SearchBase" method "generate_score" has a issue: parmameter "self.vclamp" will be assign to parmameter "bh_strategy" in class "GlobalBestPSO",class "GeneralOptimizerPSO" and class "LocalBestPSO".
Should use python keyword argument to fix it

pyswarms/utils/search/base_search.py

@@ -98,7 +98,7 @@ def generate_score(self, options):
 
         # Intialize optimizer
         f = self.optimizer(
-            self.n_particles, self.dims, options, self.bounds, self.vclamp
+            self.n_particles, self.dims, options, self.bounds, velocity_clamp=self.vclamp
         )
 
         # Return score