fix: removes ci run on push to master

this moves the ci run when there is a pull request on
the master branch, if this succeeds then it should be good
to merge changes into master

the publish action runs test before we push to pypi

note that pypi has a restriction where a filename cannot be used
https://pypi.org/help/#file-name-reuse
once it has been published, this means we will have a few rouge
alpha file releases to test the auto publish

for most use cases we should ignore the alpha releases as they
will be massive on the bleeding edge

refs #16

.github/workflows/run-tests.yml

@@ -1,9 +1,6 @@
 name: ci
 run-name: Run tests by @${{ github.actor }}
 on:
-  push:
-    branches:
-      - master
   pull_request:
     branches:
       - master