multimedia/kdenlive: drop unnecessary dependency on webkit

Upstream ported to WebEngine in [1] and then dropped that in [2]

[1] https://invent.kde.org/multimedia/kdenlive/-/commit/51feccf3cc0939d42c3ff237eb17f9a6091f1dd8
[2] https://invent.kde.org/multimedia/kdenlive/-/commit/16b7e53d8da8edc9e9b366192ba3ecf98729359a