Merge pull request commons-app#1269 from commons-app/update-pr-template

Update PULL_REQUEST_TEMPLATE.md

Author: neslihanturan

PULL_REQUEST_TEMPLATE.md

@@ -4,6 +4,12 @@ Fixes #{GitHub issue number}
 
 {Describe the changes made and why they were made.}
 
+## Tests performed
+
+Tested on {API level & name of device/emulator}, with {build variant, e.g. ProdDebug}.
+
+{Please test your PR at least once before submitting.}
+
 ## Screenshots showing what changed
 
 {Only for user interface changes, otherwise remove this section. See [how to take a screenshot](https://android.stackexchange.com/questions/1759/how-to-take-a-screenshot-with-an-android-device)}