Run CI on pull requests as well as pushes (#15)

Co-authored-by: Maxim Shulga <maxim.shulga@alludo.com>
Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>

.github/workflows/run_tests.yml

@@ -1,6 +1,6 @@
 name: Run tests
 
-on: [push]
+on: [push, pull_request]
 
 jobs:
   test:

IMPROVEMENTS.md

@@ -155,7 +155,7 @@ Acceptance criteria:
 
 ### Strengthen tests and CI
 
-- [ ] Run CI on pull requests as well as pushes.
+- [x] Run CI on pull requests as well as pushes.
 - [ ] Add macOS CI because macOS is an advertised platform.
 - [x] Fix the Unix-socket path test that currently fails on a local macOS run.
 - [ ] Replace nonexistent issue references in `xfail` markers with real tracked