Use again v18.6.4_apr21p1 on debian11

.gitlab-ci.yml

@@ -263,9 +263,9 @@ FileLicenceCheck:
     CONFIGFILE: "/cvmfs/cbm.gsi.de/$OS/bin/setup_development_environment_test.sh"
 
 .singularity_debian11_variables_apr21: &singularity_debian11_variables_apr21
-    CONTAINER: "/cvmfs/cbm.gsi.de/containers/debian11_v18.6.4_apr21p2.sif"
+    CONTAINER: "/cvmfs/cbm.gsi.de/containers/debian11_v18.6.4_apr21p1.sif"
     OS: debian11
-    FAIRSOFT_VERSION: apr21p2
+    FAIRSOFT_VERSION: apr21p1
     FAIRROOT_VERSION: v18.6.4
     BASE_PATH: "/opt/"
     SIMPATH: "$BASE_PATH/fairsoft/${FAIRSOFT_VERSION}"