.github: add pull request template

.github/pull_request_template.md

@@ -0,0 +1,28 @@
+<!-- Mark items with [x] where applicable -->
+
+#### General
+- [ ] This is a new package and it conforms to the [quality requirements](https://github.com/void-linux/void-packages/blob/master/Manual.md#quality-requirements)
+
+#### Have the results of the proposed changes been tested?
+- [ ] I use the packages affected by the proposed changes on a regular basis and confirm this PR works for me
+- [ ] I generally don't use the affected packages but briefly tested this PR
+
+<!--
+If GitHub CI cannot be used to validate the build result (for example, if the
+build is likely to take several hours), make sure to include "[ci skip]' in
+either the PR title or this description. When skipping CI, uncomment and complete
+the following section.
+Note: for builds that are likely to complete in less than 2 hours, it is not
+acceptable to skip CI.
+-->
+<!-- 
+#### Does it build and run successfully? 
+(Please choose at least one native build and, if supported, at least one cross build. More are better.)
+- [ ] I built this PR locally for my native architecture, (ARCH-LIBC)
+- [ ] I built this PR locally for these architectures (if supported. mark crossbuilds):
+  - [ ] aarch64-musl
+  - [ ] armv7l
+  - [ ] armv6l-musl
+
+[ci skip]
+-->