Fix broken URL in CODE_OF_CONDUCT.md

CODE_OF_CONDUCT.md

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 # Code of Conduct
 This repository is governed by CERN's code of conduct:
-https://hr-dep.web.cern.ch/content/code-of-conduct
+https://hr.web.cern.ch/codeofconduct
 
 __"CERN's values are commitment, professionalism, creativity, diversity and integrity. Taken together they provide the basis for respect: respect for others, respect for the Organization and respect for its mission, and underpin the CERN Code of Conduct."__