algo/tests/data: put back 'make demo'

Thanks to the previous commit of @mikael-s.
8 jobs for feature-a/3003-make-sequence in 28 minutes and 27 seconds (queued for 1 second)
Name Stage Failure
algo_valgrind_functional Valgrind Functional There is an unknown failure, please try again
make[2]: *** [should-get-tests/chimera-fake-D.tap] Error 1
make[2]: Leaving directory '/home/gitlab-runner/builds/fcaaa996/0/vidjil/vidjil/algo/tests'
Makefile:119: recipe for target 'valgrind_should' failed
make[1]: *** [valgrind_should] Error 2
make[1]: Leaving directory '/home/gitlab-runner/builds/fcaaa996/0/vidjil/vidjil/algo/tests'
Makefile:187: recipe for target 'valgrind_should' failed
make: *** [valgrind_should] Error 2
make: Leaving directory '/home/gitlab-runner/builds/fcaaa996/0/vidjil/vidjil/algo'
ERROR: Job failed: exit status 1