fix: Add license declaration [skip ci] (#1672)

Author: BenLloydPearson

.github/PULL_REQUEST_TEMPLATE.md

@@ -9,3 +9,6 @@
 ## References
 
 <!-- Links or resources that help clarify and support your intentions (e.g., Github issue) -->
+
+## License
+I confirm that this contribution is made under a BSD license and that I have the authority necessary to make this contribution on behalf of its copyright owner.