Clean-up after the repository move

[TuThoThai]

To be done by @TuThoThai with the support of @haeckerbaer, @skinkie, and @thbar:

• Check all CI and GitHub actions
• Change all links in the readme.md
• Change all links in the XSD, if any

[TuThoThai]

As of 21 July 2021:

• CI and GitHub actions have been fixed in Update CI workflow to use conditional token #229
• Change of links in readme.md are suggested in PR Update to readme #233
• There is no link in the XSD that refers to the former GitHub organisation