linguist Identify `.pubxml` as XML

Description

Checklist:

[x] I am adding a new extension to a language.
- [x] The new extension is used in hundreds of repositories on GitHub.com
  - Search results for each extension:
    - https://github.com/search?q=path%3A*.pubxml+NOT+is%3Afork&type=code&ref=advsearch
- [x] I have included a real-world usage sample for all extensions added in this PR:
  - Sample source(s):
    - https://github.com/ultraslayyy/I-am-bored/blob/info/notepad%23/src/Properties/PublishProfiles/Win64.pubxml
  - Sample license(s): GNU GPL v3.0

Oct 16 '25 01:10 ultraslayyy

Ok I have done that :)

Oct 17 '25 07:10 ultraslayyy

https://github.com/ultraslayyy/linguist/blob/main/samples/XML/Win64.pubxml

A link to your fork of this repo is not the original source. Please update this link to the original source of the sample and state the license (you've deleted the license point from the template).

Oct 17 '25 08:10 lildude

I think I fixed it. I'm sorry if I haven't, my brain just isn't at 100% rn :)

Oct 17 '25 12:10 ultraslayyy

Ooops. I forgot the XML strategy test needs modification too.

You can fix the failing test by adding the sample path to the array in the test:

https://github.com/github-linguist/linguist/blob/2409807814a3ff386294b1f217b886a1594642cd/test/test_strategies.rb#L176-L195

Oct 17 '25 13:10 lildude