erp5: use recent gcc

gcc-5.5 compiles a bit slower python and we are observing failures in
ERP5 performance tests.

stack/erp5/buildout.cfg

@@ -85,9 +85,9 @@ parts +=
   jupyter-notebook-initialized-scripts
 
 [gcc]
-# KumoFS is known not to build with gcc>6.
-# It may work with slightly more recent but not tested.
-part = gcc-5.5
+# We want a recent gcc for performance, also with fortran support for scientific python.
+part = gcc-8.2
+
 
 # override instance-jupyter-notebook not to render into default template.cfg
 [instance-jupyter-notebook]