Expand security file path (#298)

Author: lu-ohai

ads/common/auth.py

@@ -889,11 +889,12 @@ def _read_security_token_file(self, security_token_file: str) -> str:
         str:
             Security token string.
         """
-        if not os.path.isfile(security_token_file):
+        expanded_path = os.path.expanduser(security_token_file)
+        if not os.path.isfile(expanded_path):
             raise ValueError("Invalid `security_token_file`. Specify a valid path.")
         try:
             token = None
-            with open(security_token_file, 'r') as f:
+            with open(expanded_path, 'r') as f:
                 token = f.read()
             return token
         except: