MFH: r536008

multimedia/dav1d: update to 0.7.0

Changes: https://code.videolan.org/videolan/dav1d/tags/0.7.0
Changes: https://code.videolan.org/videolan/dav1d/blob/0.7.0/NEWS
Changes: https://code.videolan.org/videolan/dav1d/compare/0.6.0...0.7.0
Approved by: ports-secteam blanket (required by Firefox 78)