Fix Could not find zip member error on Serverless env

[jbajou]

1️⃣ Why should it be added? What are the benefits of this change?
As mentioned here PR 4034 introduced an issue on Vapor.
Exports can't run as they fail with error

Could not find zip member zip:///tmp/laravel-excel-OrUefjdHl3lJ6LOvPp1RUrGwetvZuKEg.xlsx#_rels\.rels

2️⃣ Does it contain multiple, unrelated changes? Please separate the PRs out.
Only this

3️⃣ Does it include tests, if possible?
No test as I could not find much testing about this class either way

4️⃣ Any drawbacks? Possible breaking changes?
I don't think so

5️⃣ Mark the following tasks as done:

• [x ] Checked the codebase to ensure that your feature doesn't already exist.
• [x ] Take note of the contributing guidelines.
• [x ] Checked the pull requests to ensure that another person hasn't already submitted a fix.
• Added tests to ensure against regression.

6️⃣ Thanks for contributing! 🙌
thanks

[patrickbrouwers]

Waiting for confirmation of other people using Vapor that this fix works for them too