Fix Jpp build

.gitlab-ci.yml

@@ -35,4 +35,11 @@ build-jpp-12.1.0:
     image: docker.km3net.de/jpp:v12-1-0
     stage: build
     script:
+        - yum install -y epel-release
+        - yum install -y python-pip python-devel
+        - _CWD=$(pwd) && cd /usr/local/root && source bin/thisroot.sh && cd $_CWD
+        - which -a root
+        - which -a python
+        - python -c "import ROOT"
+        - source /Jpp/setenv.sh /Jpp
         - *virtualenv_definition