Remove Kdenlive adapter for split out (#1438)

As part of the ongoing outlining process of contrib adapters, this removes the Kdenlive adapter from the core repository.
As discussed with the Kdenlive team (of which @vpinon, the original author, is part), the code has been moved to the KDE GitLab https://invent.kde.org/multimedia/kdenlive-opentimelineio

Related #1378

Signed-off-by: Julius Künzel <[email protected]>

Author: jlskuz

contrib/opentimelineio_contrib/adapters/contrib_adapters.plugin_manifest.json

@@ -48,12 +48,6 @@
             "name": "xges",
             "filepath": "xges.py",
             "suffixes": ["xges"]
-        },
-        {
-            "OTIO_SCHEMA": "Adapter.1",
-            "name": "kdenlive",
-            "filepath": "kdenlive.py",
-            "suffixes": ["kdenlive"]
         }
     ],
     "schemadefs" : [