To change the PR template to have 202305 (#15513)

Why I did it
To include 202305 in the PR template.

Work item tracking
Microsoft ADO (21450860):
How I did it
Change the temlate.

How to verify it
pass PR test.

Author: StormLiangMS

.github/pull_request_template.md

@@ -40,6 +40,7 @@ If PR needs to be backported, then the PR must be tested against the base branch
 - [ ] 202111
 - [ ] 202205
 - [ ] 202211
+- [ ] 202305
 
 #### Tested branch (Please provide the tested image version)