Update bug_report.md

Author: reda-alaoui

.github/ISSUE_TEMPLATE/bug_report.md

@@ -7,7 +7,7 @@ assignees: ''
 
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-<!-- Issue not following this template will be systematically rejected -->
+<!-- Issues not following this template will be systematically rejected -->
 
 **What steps will reproduce the problem?**
 Steps to reproduce the behavior: