software/beremiz-runtime: Downgrade pip, wheel and setuptools

This SR is kept separate because it is not part of current tests.

software/beremiz-runtime/software.cfg

@@ -11,6 +11,9 @@ extends =
   ../../stack/monitor/buildout.cfg
   ../../stack/slapos.cfg
 
+# Python2 versions for buildout (keep last)
+  ../../stack/slapos-py2.cfg
+
 parts =
   beremiz-source
   slapos-cookbook
@@ -20,9 +23,6 @@ parts =
   open62541
   gcc-10.2
 
-[python]
-part = python2.7
-
 [gcc]
 part = gcc-10.2