Add support for distil-large-v3 (#755)

* add distil-large-v3

* Update README.md

* use fp16 weights from Systran

faster_whisper/utils.py

@@ -25,6 +25,7 @@ _MODELS = {
     "distil-large-v2": "Systran/faster-distil-whisper-large-v2",
     "distil-medium.en": "Systran/faster-distil-whisper-medium.en",
     "distil-small.en": "Systran/faster-distil-whisper-small.en",
+    "distil-large-v3": "Systran/faster-distil-whisper-large-v3",
 }