Changelo:
==============
- #2189 Assigning named styles doesn't work
- #2190 Problems caused when saving workbooks created by LibreOffice
- Python 3.6 and 3.7 are no longer supported.
Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>
