Fix FFProbe keywords as String

[dax]

ffprobe version 4.4.2 returns a string for tags like com.apple.quicktime.keywords:

example:

    "format": {
        ...
        "tags": {
            ...
            "com.apple.quicktime.keywords": "keyword"
        }
    }

If the value is a string, this patch splits on a comma multiple keywords.

[sonarcloud]

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0 Bugs
0 Vulnerabilities
0 Security Hotspots
1 Code Smell

No Coverage information
0.0% Duplication

[qwerty287]

I think it would be good to have an end-to-end test for this, i.e. add a video file that has these keywords and then parse the file (also in addition to the current tests).

Or is this something specific for a version of ffprobe and not for a file?

[dax]

@qwerty287 I don't think it comes from a specific file as I have used such files for a long time and it only recently stopped working. The only thing that has changed is Lychee and probably ffprobe.