Fix python dependencies

Writing depends=('python python-dateutil') checks for the package "python python-dateutil which cannot be resolved
There are two ' missing (or remove them, should be valid too)

As a note and the way I did. Since python{,2}-dateutil depends on python{,2} it's not necessary to add those.

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Hey. thanks for maintaining the PKGBuild on the AUR. But there is one issue
The depends string includes two packages. But currently they're interpreted as one string/package.

Best regards