Restore test trigger on pull requests

Author: vlvkobal

.github/workflows/wireshark-test.yml

@@ -5,6 +5,10 @@ on:
     paths:
       - '.github/workflows/wireshark-test.yml'
       - 'wireshark/**'
+  pull_request:
+    paths:
+      - '.github/workflows/wireshark-test.yml'
+      - 'wireshark/**'
 
 jobs:
   run-wireshark-tests: