Add filter union

[lyf2000]

Trac ticket number

ticket-[28519]

Branch description

Provide a concise overview of the issue or rationale behind the proposed changes.

Checklist

• This PR targets the main branch.
• The commit message is written in past tense, mentions the ticket number, and ends with a period.
• I have checked the "Has patch" ticket flag in the Trac system.
• I have added or updated relevant tests.
• I have added or updated relevant docs, including release notes if applicable.
• For UI changes, I have attached screenshots in both light and dark modes.

[github-actions]

Hello! Thank you for your contribution 💪

As it's your first contribution be sure to check out the patch review checklist.

If you're fixing a ticket from Trac make sure to set the "Has patch" flag and include a link to this PR in the ticket!

If you have any design or process questions then you can ask in the Django forum.

Welcome aboard ⛵️!

[shangxiao]

The ticket mentions this is a WIP, it would be helpful to also change this PR to "draft" :)

[lyf2000]

@shangxiao I made some changes and tests started to fail, can you please help me with running tests in debug? I dk how to launch test in vscode(

[shangxiao]

@shangxiao I made some changes and tests started to fail, can you please help me with running tests in debug? I dk how to launch test in vscode(

Here's the guide for running tests locally: https://docs.djangoproject.com/en/5.0/internals/contributing/writing-code/unit-tests/

I don't use vscode myself but I reckon there must be a way ;)

PS: You'll be better off asking for help over on the Django Discord as there are heaps of friendly active community members, whereas I'm on & offline depending on $job requirements/timezone/etc. Discord: https://www.djangoproject.com/community/