publication.md: Link to CLIPol homepage is broken

[andreas-bauer]

CLIPol homepage doesn't exist anymore under the provided link.

Could you please adjust the entry for CLIPol by providing another link if the project still exists, or mark it as not available/maintained anymore.

[Toniprni]

Thank you for your interest

We placed an inquiry to the maintainers on whether or not CLIPol still exists. The information will be corrected on our next update.

The next version of the landscape survey is under work and the work in progress can be seen in the dev branch, where as of now the aforementioned is corrected (https://github.com/doubleopen-project/doubleopen-publications/blob/dev/publication.md).