update testing versions on PR template

Author: pdxmele

.github/PULL_REQUEST_TEMPLATE.md

@@ -15,8 +15,8 @@ Please include link to open issue if applicable.
 
 * I've tested for Ruby versions:
 
-- [ ] 2.2.5
-- [ ] 2.3.1
+- [ ] 2.6.7
+- [ ] 2.7.2
 
 ### Airship Contribution Agreement
 [Link here](https://docs.google.com/forms/d/e/1FAIpQLScErfiz-fXSPpVZ9r8Di2Tr2xDFxt5MgzUel0__9vqUgvko7Q/viewform)