Run github actions on pull request

pganssle · pganssle · commit af51500a8d64 · 2020-10-22T13:57:11.000-04:00
When this was in my personal namespace and I was the only one
contributing `push` was effectively the same as `pull_request`, but now
it turns out the GitHub actions haven't been triggering! Alas.
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
@@ -1,6 +1,6 @@
 name: tzdata contents
 
-on: [push]
+on: [pull_request]
 
 jobs:
   tests:
