There is a new pull request by mobinmob against master on the void-packages repository

https://github.com/mobinmob/void-packages arc-theme
https://github.com/void-linux/void-packages/pull/33723

arc-theme: update to 20211018.
Also:
- add gtk4-devel to makedepends (gtk4 theme support).

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#### General
- [ ] This is a new package and it conforms to the [quality requirements](https://github.com/void-linux/void-packages/blob/master/Manual.md#quality-requirements)

#### Have the results of the proposed changes been tested?
- [ ] I use the packages affected by the proposed changes on a regular basis and confirm this PR works for me
- [x] I generally don't use the affected packages but briefly tested this PR

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A patch file from https://github.com/void-linux/void-packages/pull/33723.patch is attached