BUG: Minor HTML formatting error in Styler.render(): rowspan attribute should use quotes

[fwt]

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pandas.

• (optional) I have confirmed this bug exists on the master branch of pandas.

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Note: Please read this guide detailing how to provide the necessary information for us to reproduce your bug.

Code Sample, a copy-pastable example

df = pd.DataFrame(data=[[1, 2]], index=[["l0", "l0"], ["l1a", "l1b"]])
s = Styler(df, uuid="_", cell_ids=False)
assert '<th id="T__level0_row0" class="row_heading level0 row0" rowspan="2">l0</th>' in s.render()

Problem description

This issue is very similar to #35706. The colspan attribute has been fixed in #36223 but the rowspan attribute hasn't been fixed yet. Fixing this would improve HTML correctness and make the Styler.render() behavior more consistent.

Compare line 330 (colspan attribute) and line 376 (rowspan attribute).

Expected Output

The rowspan attribute uses quotes and the assert statement doesn't fail.

Output of pd.show_versions()

INSTALLED VERSIONS

commit : db08276
python : 3.8.5.final.0
python-bits : 64
OS : Linux
OS-release : 4.19.76-linuxkit
Version : #1 SMP Tue May 26 11:42:35 UTC 2020
machine : x86_64
processor :
byteorder : little
LC_ALL : None
LANG : C.UTF-8
LOCALE : en_US.UTF-8

pandas : 1.1.3
numpy : 1.19.2
pytz : 2020.1
dateutil : 2.8.1
pip : 20.1.1
setuptools : 50.3.0
Cython : None
pytest : None
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : None
lxml.etree : None
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : 2.11.2
IPython : 7.18.1
pandas_datareader: None
bs4 : None
bottleneck : None
fsspec : None
fastparquet : None
gcsfs : None
matplotlib : 3.3.2
numexpr : None
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : None
pytables : None
pyxlsb : None
s3fs : None
scipy : 1.5.2
sqlalchemy : None
tables : None
tabulate : None
xarray : None
xlrd : None
xlwt : None
numba : None

[JoseNavy]

I was able to reproduce this bug in master, so I will try to fix it!

[simonjayhawkins]

closed in #38533