fix(semver): Add a necessary grouping

[futsuuu]

This PR fixes an issue where if the prerelease starts and ends with a number, it is judged as a number.

before

const version = "1.0.0-1b3" // prerelease: "1b3", but matches with /^0|[1-9]\\d*$/
parse(version).prerelease   // -> [ 1 ]

after

const version = "1.0.0-1b3" // prerelease: "1b3", doesn't match with /^(0|[1-9]\\d*)$/
parse(version).prerelease   // -> [ "1b3" ]

[CLAassistant]

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[kt3k]

LGTM. Thanks for the fix.

[kt3k]

Note: Ids like 1b3 should be considered alphanumeric identifier (because it includes b char), but currently it's handled like numeric identifier because of this error. This PR fixes it. ref. https://semver.org/#spec-item-9