fix: fix error 'str' object has not attribute 'get' (rate limit); add AlreadyFollowing exception on follow

itd/exceptions.py

@@ -102,4 +102,8 @@ class PinNotOwned(Exception):
 
 class NoContent(Exception):
     def __str__(self) -> str:
-        return 'Content or attachments required'
+        return 'Content or attachments required'
+
+class AlreadyFollowing(Exception):
+    def __str__(self) -> str:
+        return 'Already following user'