Remove -executable flag

.github/Dockerfile

@@ -10,7 +10,7 @@ RUN readlink /sage/venv >> /sage/venv_link
 WORKDIR /sage
 
 # Strip executables in /sage
-RUN LC_ALL=C find local src pkgs -executable -type f -exec strip '{}' ';' 2>&1 | grep -v "file format not recognized" || true
+RUN LC_ALL=C find local src pkgs -type f -exec strip '{}' ';' 2>&1 | grep -v "file format not recognized" || true
 
 # To exclude doc directory in the next stage
 RUN rm -rf local/share/doc