fix retreiving short sha

Author: cometkim

.github/workflows/ci.yml

@@ -509,8 +509,8 @@ jobs:
 
       - name: Install ReScript package
         run: |
-          COMMIT_SHA="$(git rev-parse --short HEAD)"
-          npm i --no-audit "https://pkg.pr.new/rescript-lang/rescript@$COMMIT_SHA"
+          COMMIT_SHA="${{ github.sha }}"
+          npm i --no-audit "https://pkg.pr.new/rescript-lang/rescript@${COMMIT_SHA::7}"
         shell: bash
         working-directory: ${{ steps.tmp-dir.outputs.path }}