ESP32-S3 example: update heapless to 0.9.1

Author: sourcebox

examples/example-esp32s3/Cargo.toml

@@ -15,4 +15,4 @@ esp-bootloader-esp-idf = { version = "0.3.0", features = ["esp32s3"] }
 usb-device = { version = "0.3.2", features = ["control-buffer-256"] }
 usbd-midi = { path = "../../" }
 midi-convert = "0.2.0"
-heapless = "0.8.0"
+heapless = "0.9.1"