remove triggering on push; only trigger on pre-release

Author: alistairewj

.github/workflows/prerelease_bigquery.yml

@@ -5,10 +5,6 @@ name: Pre-release concept build on mimiciv_derived
 on:
   release:
     types: [prereleased]
-  # TEMP: test on push to branch
-  push:
-    branches:
-      - alistair/more_gh_action_shenanigans
 
 jobs:
   build-and-validate: