As of now, the update command fails with an IndexError using current
versions of pip. If a package is already of the latest version, there is
no "Requirement already up-to-date" line present anymore. And since
nothing is installed, there is no "Successfully installed" string
either, so it fails later. So now it checks, that "Collecting yt-dlp"
line is missing instead. This works in older versions of pip as well.
Another issue is that since botamusique uses yt-dlp now instead of
youtube-dl, it was trying to update the wrong package. So the package
name was extracted as a constant and was changed to yt-dlp.
Additional minor fix in the output message. Before there was no spacing
between the botamusique version message and the YouTube package one. Now
it starts on a separate line.
