Constrain PyAV when installing whisper-ctranslate2 (#7815)

* Constrain PyAV when installing whisper-ctranslate2

PyAV 19 (2026-09-29, Python 3.12+) removed the metadata_errors argument of
av.open(). faster-whisper 1.2.1, which whisper-ctranslate2 0.4.4 installs,
still passes it, so a freshly auto-installed engine fails every
transcription and no transcript file is written.

* Prefer upgrading to latest whisper ctranslate

---------

Co-authored-by: Chocobozzz <me@florianbigard.com>

packages/tests/src/transcription/whisper/whisper-ctranslate2.spec.ts

@@ -25,7 +25,7 @@ describe('Whisper CTranslate2 transcriber', function () {
       command: 'whisper-ctranslate2',
       supportedModelFormats: [ 'CTranslate2' ],
       languageDetection: true,
-      version: '0.4.4'
+      version: '0.5.8'
     },
     logger: createConsoleLogger()
   })

packages/transcription/src/whisper/engines.ts

@@ -23,6 +23,6 @@ export const engines: TranscriptionEngine[] = [
     license: 'MIT',
     supportedModelFormats: [ 'CTranslate2' ],
     languageDetection: true,
-    version: '0.4.4'
+    version: '0.5.8'
   }
 ]