ci: change event triggers for benchmark CI to include forks (#840)

Co-authored-by: Jean Cvllr <[email protected]>

.github/workflows/benchmark.yml

@@ -8,7 +8,7 @@ on:
   # enable to run workflow manually
   workflow_dispatch:
 
-  pull_request:
+  pull_request_target:
     types: [opened]
 
     # compare gas diff only when editing Solidity smart contract code