Alter behaviour of --skip-dl to allow DRM licensing

Most people used --skip-dl just to license the DRM pre-v1.3.0. Which makes sense, --skip-dl is otherwise a pointless feature. I've fixed it so that --skip-dl worked like before, allowing license calls, while still supporting the new per-segment features post-v1.3.0.

Fixes #37

devine/core/manifests/dash.py

@@ -283,6 +283,7 @@ class DASH:
         save_path: Path,
         save_dir: Path,
         stop_event: Event,
+        skip_event: Event,
         progress: partial,
         session: Optional[Session] = None,
         proxy: Optional[str] = None,
@@ -458,6 +459,10 @@ class DASH:
             else:
                 drm = None
 
+            if skip_event.is_set():
+                progress(downloaded="[yellow]SKIPPED")
+                return
+
             def download_segment(filename: str, segment: tuple[str, Optional[str]]) -> int:
                 if stop_event.is_set():
                     # the track already started downloading, but another failed or was stopped