Force contributors to define Apache 2.0 license for the new PRs.

Author: asmorkalov

.github/PULL_REQUEST_TEMPLATE.md

@@ -2,8 +2,8 @@
 
 See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request
 
-- [ ] I agree to contribute to the project under Apache 2 License.
-- [ ] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
+- [x] I agree to contribute to the project under Apache 2 License.
+- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
 - [ ] The PR is proposed to the proper branch
 - [ ] There is a reference to the original bug report and related work
 - [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable