Fix Python fallback in configure.ac

Commit 2bd410ecdb366083fe9b4e5f6ac4b741b624230b (ticket 8709)
contained a typo "text" for "test", preventing the Python path check
from falling back from python2 to python.  This is now a fallback from
python3 to python, but the typo remains.  Fix it now.

Based on a patch by Michael Osipov.

(cherry picked from commit b7c260b22c5d815b83ff37a35569e07e847cd9c3)

https://github.com/krb5/krb5/commit/ed33a70c32f14cfe4cbbf3f490842b1fd1ef57f0
Author: Greg Hudson <ghudson@mit.edu>
Commit: ed33a70c32f14cfe4cbbf3f490842b1fd1ef57f0
Branch: krb5-1.17
 src/configure.in |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)