also try running bzip2 in workflow to test container building

Author: boegel

.github/workflows/container_tests.yml

@@ -89,4 +89,5 @@ jobs:
           export EASYBUILD_CONTAINERPATH=$PWD
           export EASYBUILD_CONTAINER_CONFIG='bootstrap=yum,osversion=7'
           eb bzip2-1.0.8.eb --containerize --experimental --container-build-image
-          test -f bzip2-1.0.8.sif
+          singularity exec bzip2-1.0.8.sif command -v bzip2 | grep '/app/software/bzip2/1.0.8/bin/bzip2' || (echo "Path to bzip2 '$which_bzip2' is not correct" && exit 1)
+          singularity exec bzip2-1.0.8.sif bzip2 --help