Fedora: Update required RPMs for Fedora 31

This includes the addition of the python3-virtualenv package required to
provide the virtualenv binary that is no longer present in the image.

Change-Id: Ie8e66d8b9f93063b97f88f41a626daddf235339b
diff --git a/files/rpms/dstat b/files/rpms/dstat
index e63af31..a091cce 100644
--- a/files/rpms/dstat
+++ b/files/rpms/dstat
@@ -1,2 +1,2 @@
-dstat # not:f30
-pcp-system-tools # dist:f30
+dstat # not:f30,f31
+pcp-system-tools # dist:f30,f31