Fix typo separately

Author: poyea

graphs/breadth_first_search_shortest_path.py

@@ -32,7 +32,7 @@ def shortest_path(self, target_vertex):
         """This shortest path function returns a string, describing the result:
         1.) No path is found. The string is a human readable message to indicate this.
         2.) The shortest path is found. The string is in the form `v1(->v2->v3->...->vn)`,
-            where v1 is the source vertex and vn is the target vertex, if it exists seperately.
+            where v1 is the source vertex and vn is the target vertex, if it exists separately.
         """
         if target_vertex == self.source_vertex:
             return f"{self.source_vertex}"