added Literal definitions as suggested and fixed pylint issues

Author: tcfranks

adafruit_max31856.py

@@ -376,7 +376,7 @@ def _wait_for_oneshot(self) -> None:
         while self.oneshot_pending:
             sleep(0.01)
 
-    def _read_register(self, address: int, length: int) -> int:
+    def _read_register(self, address: int, length: int) -> bytearray:
         # pylint: disable=no-member
         # Read a 16-bit BE unsigned value from the specified 8-bit address.
         with self._device as device: