fix: update CERT contact link for responsible issue reporting

Author: t3chn0m4g3

README.md

@@ -958,7 +958,7 @@ Storage failures can be identified easier via `htop`.
 # Contact
 T-Pot is provided ***as is*** open source ***without*** any commitment regarding support ([see the disclaimer](#disclaimer)).
 
-If you are a security researcher and want to responsibly report an issue please get in touch with our [CERT](https://www.telekom.com/en/company/data-privacy-and-security/news/introducing-deutsche-telekom-cert-358316).
+If you are a security researcher and want to responsibly report an issue please get in touch with our [CERT](https://www.telekom.com/en/about-us/data-privacy-and-security/working-together-for-security/telekom-cert).
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 ## Issues