added reesearcher manager for secretary

backend/src/main/java/ovh/herisson/Clyde/Services/ScientificPublications/ResearchesService.java

@@ -114,6 +114,14 @@ public class ResearchesService {
     }
 
     public void deleteResearcher(Researcher researcher) {
+        articleRepo.findAll();
+        for (Research r: articleRepo.findAll())
+        {
+            if (r.getCoAuthors().contains(researcher)){
+                r.getCoAuthors().remove(researcher);
+                articleRepo.save(r);
+            }
+        }
        researcherRepo.delete(researcher);
     }