BUG: DataFrame.explode fails with str dtype

[rhshadrach]

• closes #xxxx (Replace xxxx with the GitHub issue number)
• Tests added and passed if fixing a bug or adding a new feature
• All code checks passed.
• Added type annotations to new arguments/methods/functions.
• Added an entry in the latest doc/source/whatsnew/vX.X.X.rst file if fixing a bug or adding a new feature.

This operation works on all other dtypes, e.g.

df = pd.DataFrame({"a": [1, 2]})
print(df.explode(column="a"))
#    a
# 0  1
# 1  2

[datapythonista]

Looks good. I'd personally have the new release notes template added in a separate issue, but no big deal.

Btw, did we have problems before to have the result is not df assert? I haven't used it before, it'd be good to understand in which tests it make sense. Thanks!

[rhshadrach]

@datapythonista

Btw, did we have problems before to have the result is not df assert? I haven't used it before, it'd be good to understand in which tests it make sense. Thanks!

I think it makes sense to check this when we have a no-op that should return a copy. If the operation modifies the data (which is the case for the vast majority of tests), I don't think it needs to be checked.

[rhshadrach]

@datapythonista - fixed up the docs build, this should be ready.