Try converting output to string before storing it in github output

.github/workflows/frontend-test-action.yml

@@ -22,11 +22,24 @@ jobs:
       - name: Run unit tests
         run: npm test
 
+  get-e2e-files:
+    runs-on: ubuntu-24.04
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Generate file list
+        id: generate-file-list
+        run: |
+          FILES=$(ls -1 "./frontend/cypress/e2e/" | jq -R | jq -s | jq -R)
+          echo "file_list=$FILES" >> "$GITHUB_OUTPUT"
+
   e2e:
+    needs: get-e2e-files
     runs-on: ubuntu-24.04
     strategy:
       matrix:
-        file: "['checkIn.cy.ts', 'crud.cy.ts', 'duplicated-scoring.cy.ts', 'keyresult.cy.ts', 'login.cy.ts', 'objective.cy.ts', 'objective-backlog.cy.ts', 'overview.cy.ts', 'scoring.cy.ts', 'tab.cy.ts', 'team.cy.ts', 'teammanagement.cy.ts']"
+        file: ${{ fromJSON(needs.get-e2e-files.outputs.file_list) }}
     steps:
       - name: Checkout
         uses: actions/checkout@v4