Remove Fedora 30 support

Fedora 30 hit EOL earlier in the year and can be removed from devstack.

https://en.wikipedia.org/wiki/Fedora_version_history#Version_history

Change-Id: I47452700d520a544c93c0c187143ec763f026612
diff --git a/lib/nova b/lib/nova
index c1354e7..9d7bbd8 100644
--- a/lib/nova
+++ b/lib/nova
@@ -293,8 +293,8 @@
             fi
         fi
 
-        if is_fedora && [[ $DISTRO =~ f3[0-1] ]]; then
-            # For f30 and f31 use the rebased 2.1.0 version of the package.
+        if is_fedora && [[ $DISTRO =~ f31] ]]; then
+            # For f31 use the rebased 2.1.0 version of the package.
             sudo dnf copr enable -y lyarwood/iscsi-initiator-utils
             sudo dnf update -y
         fi