[Bug]: [Calendar] The label for the week number column is missing

[desig9stein]

Which component(s) are affected?

Calendar

Description

The label for the week number column is missing for all themes.

Reproduction

1. Open the calendar in the master branch
2. Show the week number column from the actions panel

Workaround

No

Is this a regression?

Yes. This used to work, but now it doesn't.

Affected versions

All

Browser/OS/Node environment

Browser: All,
OS: All