Update andstor/file-existence-action digest to 31a5027

Author: renovate[bot]

.github/workflows/test.yml

@@ -27,7 +27,7 @@ jobs:
 
       - name: "Check if repository is a Lerna monorepo"
         id: check_files
-        uses: andstor/file-existence-action@20b4d2e596410855db8f9ca21e96fbe18e12930b
+        uses: andstor/file-existence-action@31a502724c77ada11ba0b3442e34757182ccdbd3
         with:
           files: "lerna.json"