[acast] Add new extractor

youtube_dl/extractor/__init__.py

@@ -3,6 +3,10 @@ from __future__ import unicode_literals
 from .abc import ABCIE
 from .abc7news import Abc7NewsIE
 from .academicearth import AcademicEarthCourseIE
+from .acast import (
+    ACastIE,
+    ACastChannelIE,
+)
 from .addanime import AddAnimeIE
 from .adobetv import (
     AdobeTVIE,