Upgrade FFmpeg build to 6.0-scrcpy-3

Use a build which includes the opus muxer, to support recording to .opus
files.

Refs <https://github.com/rom1v/scrcpy-deps/commits/6.0-scrcpy-3>
PR #3978 <https://github.com/Genymobile/scrcpy/pull/3978>

app/prebuilt-deps/prepare-ffmpeg.sh

@@ -6,11 +6,11 @@ cd "$DIR"
 mkdir -p "$PREBUILT_DATA_DIR"
 cd "$PREBUILT_DATA_DIR"
 
-VERSION=6.0-scrcpy-2
+VERSION=6.0-scrcpy-3
 DEP_DIR="ffmpeg-$VERSION"
 
 FILENAME="$DEP_DIR".7z
-SHA256SUM=98ef97f8607c97a5c4f9c5a0a991b78f105d002a3619145011d16ffb92501b14
+SHA256SUM=36829d98ac4454d7092c72ddb92faa20b60450bc0fe8873076efb0858cdcbc2c
 
 if [[ -d "$DEP_DIR" ]]
 then