Release 1.3.8

Fixed

• Fix compile error with ESP32S3.
• Prevent a potential crash when retrieving characteristics from a service if the result was successful but no characteristics found.

Changed

• Save resources when retrieving descriptors if the characteristic handle is the same as the end handle (no descriptors).
• Subscribing to characteristic notifications/indications will now always use write with response, as per BLE specifications.
• NimBLEClient::discoverAttributes now returns a bool value to indicate success/failure