Add contributor code of conduct

CODE_OF_CONDUCT.md

+# Contributor code of conduct
+
+As contributors and maintainers of the SimCAQ project, we pledge to respect everyone who contributes by posting issues, updating documentation, submitting merge requests, providing feedback in comments, and any other activities.
+
+Communication through any of SimCAQ's channels (GitLab, Mattermos, mailing lists, etc.) must be constructive and never resort to personal attacks, trolling, public or private harrassment, insults, or other unprofessional conduct.
+
+We promise to extend courtesy and respect to everyone involved in this project regardless of gender, gender identity, sexual orientation, disability, age, race, ethnicity, religion, or level of experience. We expect anyone contributing to the SimCAQ project to do the same.
+
+If any member of the community violates this code of conduct, the maintainers of the SimCAQ project may take action, removing issues, comments, and MRs or blocking accounts as deemed appropriate.
+
+If you are subject to or witness unacceptable behavior, or have any other concerns, please contact us.
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