fix system test because of cleared variable with a clear all in the script

Author: Remi-Gau

.github/workflows/system_tests_matlab.m

@@ -9,6 +9,9 @@
 
 run test_moae;
 
+% repeat this because test_moae has a "clear all"
+root_dir = getenv('GITHUB_WORKSPACE');
+
 cd(fullfile(root_dir, 'demos', 'face_repetition'));
 
 run face_rep_resolution;