Require 4.0.1 robotframework for renode.

* Required to support renode automation.

Change-Id: I2b7b3c05ec05a1babd346e91c5917ecee8c981d3

install-prereqs.sh

diff --git a/install-prereqs.sh b/install-prereqs.sh
index 6542b52..293a96e 100755
--- a/install-prereqs.sh
+++ b/install-prereqs.sh
@@ -86,7 +86,7 @@
     camkes-deps
     sel4-deps
     setuptools
-    robotframework==3.1
+    robotframework==4.0.1
     netifaces
     pandas
     psutil