CI: Fix Mkdocs Automation

[MustafaJafar]

Changelog Description

• Add a CI action to trigger MK Docs deployment on creating new tags.
  when testing the CI action manually (trigger from Action tab manually on GH), it will generate a dummy-build version that will be deleted as soon as a tag is created.
• Revert changes in pyproject.toml from Automated mkdocs setup #52 and Automated mkdocs setup #53

resolve #64

Additional Notes

This PR ports ynput/ayon-core#1441 fixes for applications addon.
This PR add some cosmetics:

1. update light and dark mode icons.
2. move requirements file to root location of the repo to avoid moving it along with the docs build.

Testing notes:

1. go to https://docs.ayon.dev/ayon-sitesync/latest/ you should find light/dark icons are updated and the latest is pointing to test-build.
   since the workflow doesn't exist in main branch yet, I had to add on push temporarily in de1dc9f to run the action and revert it in dc6f50c.

[MustafaJafar]

This module was added in #52 and I found it is used in

ayon-sitesync/client/ayon_sitesync/addon.py

Lines 871 to 880 in 0d2da31

	try:
	import requests
	except Exception:
	self.log.warning(
	"Couldn't add sites to representations "
	"('requests' is not available)"
	)
	return
	requests.post(rest_api_url)

I'm not sure if I should remove it as well. or should add it to client's pyproject.toml