Update lab_utils_uni.py

Fixes C1_W1_Lab05_Gradient_Descent_Soln.ipynb with error "OverflowError: Python int too large to convert to C long on the last graph"

C1 - Supervised Machine Learning - Regression and Classification/week1/Optional Labs/lab_utils_uni.py

@@ -297,7 +297,7 @@ def plt_divergence(p_hist, J_hist, x_train,y_train):
 
     # Print w vs cost to see minimum
     fix_b = 100
-    w_array = np.arange(-70000, 70000, 1000)
+    w_array = np.arange(-70000, 70000, 1000, dtype="int64")
     cost = np.zeros_like(w_array)
 
     for i in range(len(w_array)):
@@ -316,6 +316,8 @@ def plt_divergence(p_hist, J_hist, x_train,y_train):
     #===============
 
     tmp_b,tmp_w = np.meshgrid(np.arange(-35000, 35000, 500),np.arange(-70000, 70000, 500))
+    tmp_b = tmp_b.astype('int64')
+    tmp_w = tmp_w.astype('int64')
     z=np.zeros_like(tmp_b)
     for i in range(tmp_w.shape[0]):
         for j in range(tmp_w.shape[1]):