Fix latest plugin version not being downloaded consistently

[ShyamGadde]

Summary

Fixes #1690

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Co-authored-by: ShyamGadde <shyamgadde@git.wordpress.org>
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[westonruter]

Lastly, note that many plugins also use Stable tag: trunk: https://wpdirectory.net/search/01JDB0D3QBVXR8KWR1X9BRYYPB

I haven't seen trunk show up in the download URL, but in theory it might?

Here's another search for plugins using non-standard versions: https://wpdirectory.net/search/01JDB0R6MBNNEMH0A1X8AHKQYC

The WP Umbrella plugin version doesn't begin with a digit:

https://downloads.wordpress.org/plugin/wp-health.v2.16.4.zip

That being said, perhaps we should just strip off everything up to the first . since I don't believe any plugin is allowed to have that as a character in the slug.

[westonruter]

Again, this is all likely splitting hairs since none of the plugins we include here should ever use a non-standard version!