Add reset to the repr for Rate (#1389)

Add the reset attribute to the repr for Rate, and add a test for good
measure.

Co-Authored-By: Jonathan Leitschuh <jonathan.leitschuh@gmail.com>

github/Rate.py

@@ -37,7 +37,11 @@ class Rate(github.GithubObject.NonCompletableGithubObject):
 
     def __repr__(self):
         return self.get__repr__(
-            {"limit": self._limit.value, "remaining": self._remaining.value}
+            {
+                "limit": self._limit.value,
+                "remaining": self._remaining.value,
+                "reset": self._reset.value,
+            }
         )
 
     @property