gh-95605: Fix `float(s)` error message when `s` contains only whitespace (GH-95665) (GH-95859)

This PR fixes the error message from float(s) in the case where s contains only whitespace.
(cherry picked from commit 97e9cfa75a80b54a0630b7371f35e368a12749d1)

Co-authored-by: Mark Dickinson <dickinsm@gmail.com>
3 files changed