DOC: Fix typo of `=!` to `!=` in docstring (#36077)
DOC: Fix typo of `=!` to `!=` in docstring (#36077)

This fixes GH36075.
jorisvandenbossche/pandas,jreback/pandas,dsm054/pandas,dsm054/pandas,gfyoung/pandas,datapythonista/pandas,jorisvandenbossche/pandas,rs2/pandas,gfyoung/pandas,jreback/pandas,gfyoung/pandas,jorisvandenbossche/pandas,datapythonista/pandas,jreback/pandas,jreback/pandas,gfyoung/pandas,pandas-dev/pandas,jreback/pandas,dsm054/pandas,jorisvandenbossche/pandas,rs2/pandas,pandas-dev/pandas,pandas-dev/pandas,gfyoung/pandas,dsm054/pandas,dsm054/pandas,datapythonista/pandas,rs2/pandas,rs2/pandas,pandas-dev/pandas,datapythonista/pandas