software/slapos-testing: use gcc 8.5 on python2

SlapOS.Eggs.UnitTest-Master.Python2 also installs old scipy so it needs
old gcc

software/slapos-testing/software.cfg

@@ -42,6 +42,10 @@ parts =
 # Always build GCC for Fortran (see openblas).
 max_version = 0
 
+[gcc:python2]
+# use old gcc version for old scipy version used in python2
+part = gcc-8.5
+
 [bootstrap-slapos.recipe.cmmi]
 # install our develop version of slapos.recipe.cmmi before anything else,
 # otherwise it will be installed from pypi by dependencies.