Mark the project with an XCode 11.5 open

[dcoufal]

Description

This PR marks the project as "opened by Xcode 11.5" to skip annoying update warnings.

Pre-submission Checklist

• [x] I ran the unit tests locally before checking in.
• [x] I made sure there were no compiler warnings before checking in.
• [x] I have written useful documentation for all public code.
• [x] I have written unit tests for this new feature.