new pip only installer and workflow to test it

Author: mamueller

install_developer_pip.sh

@@ -0,0 +1,7 @@
+pip show testinfrastructure;ret=$? 
+if [ $ret -eq 0 ]; then
+    echo "allredy installed"
+else 
+    pip install -e git+https://github.com/MPIBGC-TEE/testinfrastructure.git#egg=testinfrastructure
+fi 
+    pip install -e .