fix(types): resolve 2 mypy errors surfaced by the refreshed mypy

The lockfile refresh floats mypy (^1.10.1) up to 1.20.2, which is stricter
and flags two pre-existing latent type issues that the older mypy missed:

- auth/oauth.py:48 — is_expired() returned `exp_time and (...)`, whose value
  is `Any | None` (the exp claim) when falsy, not bool, violating the
  `-> bool` annotation. Use `exp_time is not None and (...)` so the return
  is a real bool and the None-exp case is explicit.
- auth/retry.py:248 — the command_type setter was annotated
  `value: CommandType`, but the getter returns `Optional[CommandType]` and
  __private_init__ assigns an `Optional[CommandType]`. Widen the setter to
  `Optional[CommandType]` to match the getter and actual usage.

Both are type-annotation-only changes; no runtime behavior change.

Co-authored-by: Isaac
Signed-off-by: Vikrant Puppala <vikrant.puppala@databricks.com>

Author: vikrantpuppala

src/databricks/sql/auth/oauth.py

@@ -45,7 +45,7 @@ def is_expired(self) -> bool:
             exp_time = decoded_token.get("exp")
             current_time = time.time()
             buffer_time = 30  # 30 seconds buffer
-            return exp_time and (exp_time - buffer_time) <= current_time
+            return exp_time is not None and (exp_time - buffer_time) <= current_time
         except Exception as e:
             logger.error("Failed to decode token: %s", e)
             raise e

src/databricks/sql/auth/retry.py

@@ -245,7 +245,7 @@ def command_type(self) -> Optional[CommandType]:
         return self._command_type
 
     @command_type.setter
-    def command_type(self, value: CommandType) -> None:
+    def command_type(self, value: Optional[CommandType]) -> None:
         self._command_type = value
 
     @property