Fix detecting version from URL

[SeekingMeaning]

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Currently, line 264 does not work for one of the given examples unrtf_0.20.4-1

m = /[-_]((?:\d+\.)*\d\.\d+-(?:p|rc|RC)?\d+)(?:[-._](?:bin|dist|stable|src|sources))?$/.match(stem)

Looking closer, \d\.\d+ should be \d+\.\d+ where another + is added to indicate that there can be more than one digit \d.

(A similar change is made to line 353.)

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And as for line 274 m = /-((?:\d)+-\d+)/.match(stem), some redundancy can be removed by replacing (?:\d) with \d. Usually, the syntax (?:) is used either for (1) matching a group of characters without creating a capture such as (?:\d+\.)* or (2) "or" expressions such as (?:p|rc|RC). However, since it's just \d by itself, it can be simplified.

[MikeMcQuaid]

Thanks so much for your first contribution! Without people like you submitting PRs we couldn't run this project. You rock, @SeekingMeaning!