Modify StringToken::PATTERN to fix comparison

[samford]

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StringToken's PATTERN regex (/[a-z]+[0-9]*/i) is consuming numeric parts of the version string that should probably be tokenized separately as a NumericToken. As a result, you can end up with incorrect version comparisons when part of the version string consists of letters with trailing numbers.

Taking Homebrew/homebrew-core#58711 as an example, 4.0ga10 is treated as older than 4.0ga9. This is because 4.0ga10 is currently tokenized as follows:

[#<Version::NumericToken 4>,
 #<Version::NumericToken 0>,
 #<Version::StringToken "ga10">]

When ga10 is compared to ga9 (i.e., "ga10" <=> "ga9"), it's reported as being lower (-1). To address this, we can compare ga and 10/9 separately (as a StringToken and NumericToken respectively).

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This PR removes the [0-9]* from StringToken's PATTERN regex, which results in the aforementioned version being tokenized as follows:

[#<Version::NumericToken 4>,
 #<Version::NumericToken 0>,
 #<Version::StringToken "ga">,
 #<Version::NumericToken 10>]

This produces the comparison result that we would expect, where 4.0ga10 is treated as newer than 4.0ga9.

I did a full livecheck run over the homebrew-core formulae with/without the change in this PR and the only difference was with x3270. At least from the perspective of livecheck, this change doesn't seem to result in any undesirable version comparison issues.

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I've left this as a draft for the moment because I have a question about how we should be doing StringToken comparisons. It seems like we should treat ga and GA as the same, otherwise 4.0ga10 would be treated as newer than 4.0GA11. To address this, we would seemingly need to modify StringToken comparisons to ignore case.

Is anyone aware of any situations where letter case is used to indicate something newer (e.g., cycling through lowercase a-z before proceeding to uppercase A-Z)? Once we've decided how to proceed in this area, I'll add some additional tests and mark this as ready for review.

[MikeMcQuaid]

This makes sense to me. Merging as-is because it's fixing a user issue and the rest can be tackled in a future PR. Thanks @samford, great work!