Add whatsnew entry

Author: ales-erjavec

doc/source/whatsnew/v1.4.0.rst

@@ -454,6 +454,8 @@ I/O
 - Bug in unpickling a :class:`Index` with object dtype incorrectly inferring numeric dtypes (:issue:`43188`)
 - Bug in :func:`read_csv` where reading multi-header input with unequal lengths incorrectly raising uncontrolled ``IndexError`` (:issue:`43102`)
 - Bug in :func:`read_csv`, changed exception class when expecting a file path name or file-like object from ``OSError`` to ``TypeError`` (:issue:`43366`)
+- Bug in :func:`read_csv` with `float_precision="round_trip"` which did not skip initial/trailing whitespace (:issue:`43713`)
+-
 
 Period
 ^^^^^^