add pull request template

.gitee/PULL_REQUEST_TEMPLATE.md

+<!--  Thanks for sending a pull request!  Here are some tips for you:
+
+If this is your first time, please read our contributor guidelines: https://gitee.com/mindspore/mindspore/blob/master/CONTRIBUTING.md
+-->
+
+**What type of PR is this?**
+> Uncomment only one ` /kind <>` line, hit enter to put that in a new line, and remove leading whitespaces from that line:
+>
+> /kind bug
+> /kind task
+> /kind feature
+
+
+**What does this PR do / why do we need it**:
+
+
+**Which issue(s) this PR fixes**:
+<!-- 
+*Automatically closes linked issue when PR is merged.
+Usage: `Fixes #<issue number>`, or `Fixes (paste link of issue)`.
+-->
+Fixes #
+
+**Special notes for your reviewers**:
+