Mypy won't show warnings for identical open files when reporting scope is set to workspace

To repro:

1. Set `mypy-type-checker.reportingScope` to `workspace`
1. Create and save a file with any content that shows a Mypy error. For example `print("hi`
2. Then create and save another file with the same content.
3. Open them side by side and notice Mypy only shows the error for one of them:

https://github.com/microsoft/vscode-mypy/assets/45497113/e4fcd8cc-1024-40ae-bcc8-f78c9b48762b

Works as expected if scope is set to `file` instead

[mypylogs.txt](https://github.com/microsoft/vscode-mypy/files/12458006/mypylogs.txt)