split contrib check into separate file

.github/scripts/contrib.sh

@@ -0,0 +1,8 @@
+#!/bin/bash
+
+set -e
+
+headAuthor=$(git log -1 --pretty=format:'%ae')
+git log --pretty=format:'%ae' CONTRIBUTORS | grep -q "$headAuthor"
+
+echo "$headAuthor found in CONTRIBUTORS"

.github/workflows/contrib.yml

@@ -9,5 +9,4 @@ jobs:
       - uses: actions/checkout@v2
       - name: Check
         run: |
-          headAuthor=$(git log -1 --pretty=format:'%ae')
+          .github/scripts/contrib.sh
-          git log --pretty=format:'%ae' CONTRIBUTORS | grep -q "$headAuthor"