Comment shapes are changed after open files created by Excelize then save again

[xuancanh]

Description

Comment shapes are changed after open files created by Excelize then save again.

Steps to reproduce the issue:

1. Create a new excel file using Excelize.
2. Add a new comment to the excel file using Excelize.
3. Save the file.
4. Open the file.
5. Do nothing, save the file again.

Describe the results you received:

Describe the results you expected:

Output of go version:

go version go1.14.3 darwin/amd64

Excelize version or commit ID:

v2.2.0

Environment details (OS, Microsoft Excel™ version, physical, etc.):
Excel 16.39
Microsoft Windows 10 and Mac OSX Catalina