fix(system_stats): add missing regex lib

[the-homeless-god]

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Description

Hi, with latest version on BSD faced that the file of system stats missing regex import, without it doesn't build.

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[werdl]

Hi, I have fixed this properly in #1345, as on OpenBSD (haven't tested on other BSDs) battery info wasn't working at all, so I fixed that + the regex thing.

[the-homeless-god]

@werdl I think it can be simply just fix first regex and after that just jump into your fix :)