Sunburst diagram's label not working properly in 0.29.0rc7

[Yukinoshita-Yukino]

Make sure these boxes are checked before submitting your issue - thank you!

• [not relevant] I have checked the superset logs for python stacktraces and included it here as text if there are any.
• [checked] I have reproduced the issue with at least the latest released version of superset.
• [checked] I have checked the issue tracker for the same issue and I haven't found one similar.

Superset version

0.29.0rc7 (pip install superset==0.29.0rc7)

Expected results

Sunburst's label working properly.

Actual results

I set up a Sunburst diagram and it's label is just not working correctly.
I also have superset 0.28.1 installed on another machine and in this version it works fine.
Therefore this problem should be implemented between these two versions I guess.

This is how I set up my Sunburst diagram

This is how the label is in version 0.29.0rc7 which is not working correctly

This is the same diagram in version 0.28.1 which is working just fine.

Steps to reproduce

Just create any 3 layer Sunburst diagram.