package/memtester: bump version to 4.7.1
For change log, see:
https://pyropus.ca./software/memtester/CHANGELOG
Version 4.7.1 fixes compile error with stricter C23/gcc-15 due to
incompatible type declaration.
Fixes:
https://autobuild.buildroot.org/results/6d4d4e8ca4269a3d8f795c7c186ef70411f2dc79/build-end.log
Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: Julien Olivain <ju.o@free.fr>