Allow unified_strdate to handle "*3rd" in date strings.

[Nyaa-rlathotep]

Please follow the guide below

• You will be asked some questions, please read them carefully and answer honestly
• Put an x into all the boxes [ ] relevant to your pull request (like that [x])
• Use Preview tab to see how your pull request will actually look like

---

Before submitting a pull request make sure you have:

• At least skimmed through adding new extractor tutorial and youtube-dl coding conventions sections
• Searched the bugtracker for similar pull requests
• Checked the code with flake8

In order to be accepted and merged into youtube-dl each piece of code must be in public domain or released under Unlicense. Check one of the following options:

• I am the original author of this code and I am willing to release it under Unlicense
• I am not the original author of this code but it is in public domain or released under Unlicense (provide reliable evidence)

What is the purpose of your pull request?

• Bug fix
• Improvement
• New extractor
• New feature

---

Description of your pull request and other information

unified_strdate was missing "*rd" for for "3rd" and "23rd". It did have "*st", "*nd", and "*th".
Fixes #23197

[dstftw]

Add tests.

[Nyaa-rlathotep]

Roger that. Tests added, and I double-checked that the new tests failed without the first commit, and passed with it.