ci: trigger benchmarks on pull_request to any branch

Remove the 'branches: [master]' filter from the pull_request trigger
so that the benchmark jobs (including capybara comparisons) also fire
on PRs targeting capybara or any other branch.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: wdconinc

.github/workflows/build-push.yml

@@ -7,8 +7,6 @@ on:
     branches:
     - master
   pull_request:
-    branches:
-    - master
   workflow_dispatch:
     inputs:
       EDM4EIC_VERSION: