GradientOptimization: fix error on default bounds

bounds are checked only during reset, and the default value of
search_space causes this to fail (lower == upper)

psyneulink/core/components/functions/nonstateful/optimizationfunctions.py

@@ -1245,9 +1245,9 @@ def reset(self, default_variable=None, objective_function=None, context=None, **
                 # Array specified for upper bound, so replace any None's with +inf
                 upper = np.array([[float('inf')] if n[0] is None else n for n in upper.reshape(sample_len,1)])
 
-                if not all(lower<upper):
+                if not all(lower <= upper):
                     raise OptimizationFunctionError(f"Specification of {repr(BOUNDS)} arg ({bounds}) for {self.name}"
-                                                    f"{owner_str} resulted in lower >= corresponding upper for one or "
+                                                    f"{owner_str} resulted in lower > corresponding upper for one or "
                                                     f"more elements (lower: {lower.tolist()}; uuper: {upper.tolist()}).")
 
                 bounds = (lower,upper)