Add contribution checkbox to feature request template

Author: w-ahmad

.github/ISSUE_TEMPLATE/feature_request.md

@@ -18,3 +18,6 @@ A clear and concise description of any alternative solutions or features you've
 
 **Additional context**
 Add any other context or screenshots about the feature request here.
+
+### Contribution:
+- [ ] I am willing to submit a PR for this feature