Migrate webtop ubuntu-kde to s6v3

[thespad]

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• [x] I have read the contributing guideline and understand that I have made the correct modifications

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Description:

Benefits of this PR and context:

How Has This Been Tested?

Source / References:

[LinuxServer-CI]

I am a bot, here are the test results for this PR: https://ci-tests.linuxserver.io/lspipepr/webtop/ubuntu-kde-e19621da-pkg-e19621da-pr-53/index.html https://ci-tests.linuxserver.io/lspipepr/webtop/ubuntu-kde-e19621da-pkg-e19621da-pr-53/shellcheck-result.xml