ci: add missing quotes to test-latest-release workflow (#5715)

Just adding missing quotes that prevented this workflow from executing
successfully.

### QA Notes
Manually triggered and confirmed the workflow now works as expected.

.github/workflows/test-e2e-release.yml

@@ -100,7 +100,7 @@ jobs:
         id: electron-e2e-tests
         run: |
           export DISPLAY=:10
-          BUILD=/usr/share/positron npx playwright test --project e2e-electron --workers 2 --grep=${{ env.PW_TAGS }}
+          BUILD=/usr/share/positron npx playwright test --project e2e-electron --workers 2 --grep "${{ env.PW_TAGS }}"
 
       - name: Upload Playwright Report to S3
         if: ${{ !cancelled() }}