Fix url

README.md

-[![Open in Coder](https://coder.development.infs.ch/templates/docker-code-server/workspace?param.repository_url=https://gitlab.ost.ch/dominic.klinger/coder-testworkspace.git)
\ No newline at end of file
+[![Open in Coder](https://coder.development.infs.ch/open-in-coder.svg)](https://coder.development.infs.ch/templates/docker-code-server/workspace?param.repository_url=https://gitlab.ost.ch/dominic.klinger/coder-testworkspace.git)
\ No newline at end of file