make group #3 non-capturing, since we never reference it.

[natefinch]

This makes the code a little easier to follow, and we remove the nested groups which are kind of confusing.

[mbruzek]

I checked the new regular expression with https://regex101.com/ and the following versions came back correctly:

2.0-alpha2
1.  [0-1]   `2`
2.  [2-3]   `0`
3.  [4-9]   `alpha`
4.  [9-10]  `2`
1.26-beta1
1.  [0-1]   `1`
2.  [2-4]   `26`
3.  [5-9]   `beta`
4.  [9-10]  `1`
1.2.3.4
1.  [0-1]   `1`
2.  [2-3]   `2`
4.  [4-5]   `3`
5.  [5-7]   `.4`

Looking at the code, the sub 5 seems OK for this last test case. Are there tests for the version that need to be updated? Is there any other use of the version regex in the code?

[natefinch]

both are only ever used in the one spot, and there's a bunch of tests, so I'm pretty confident it's ok.

[anastasiamac]

Please resolve conflicts so that we can review.

[bz2]

LGTM.

[reedobrien]

👍 All the tests pass.

[reedobrien]

sorry, not sure how I hit the close button. must have double tabbed.