Handle Pinget no-applicable upgrade result with zero exit code

[Wojciech Bigosinski (wojciech-bigosinski)]

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Pinget can return exit code 0 while printing No applicable upgrade found. UniGetUI previously treated this result as a successful upgrade.

This change recognizes Pinget's no-applicable output even when the exit code is 0 and routes it through UniGetUI's existing not-applicable upgrade handling.