fix: added self argument for linear probe

data_structures/hash_table.py

@@ -31,7 +31,7 @@ class hash_table:
     def __len__(self):
         return self.size
 
-    def linear_probing(key):
+    def linear_probing(self, key):
         return (key + 1) % self.size
 
     def insert(self, key):