DEPR: 3.4 deprecations
- [x] file open with mode of `'rU'`: https://docs.python.org/3/library/fileinput.html (in test_sql.py), #7625

closed by #7204
- [x] to_csv writing with floating point chunksize
- [x] plotting with floating point axes slices

closed by #7162, #7164, #7165, #7166, #7172, #7182
- [x] `assert_` to `assertTrue`
- [x] `assertEquals` to `assertEqual`
- [x] `assertAlmostEquals` to `assertAlmostEqual`
