multimedia/shotcut: update to 20.07.11

From ChangeLog: https://www.shotcut.org/blog/new-release-200711/

This version fixes a few problems introduced in recent version 20.06.28:

• Fixed noisy sound playback on some Windows systems.
• Fixed UI layout glitches and default/minimum size of timeline too short.
• Fixed Quick Sync Video hardware encoder (h264_qsv or hevc_qsv withQuality-based VBR) not working on Windows on older Intel chips.
• Fixed Properties > Speed not working correctly on trimmed clip in Source player.
• Fixed Stabilize and Normalize: Two Pass filters not working on trimmed clip in Source player.

Reported by: portscout