Fix reno

Without this patch, the branch newton-eol will be used for release notes.
That branch contains a duplicated release note with wrong formatting,
which we don't want.

Change-Id: I31f816b07debc7e4856eefea9c8e8e41d8aa172c

releasenotes/config.yaml

@@ -1,3 +0,0 @@
----
-collapse_pre_releases: true
-stop_at_branch_base: false

reno.yaml

@@ -0,0 +1,2 @@
+---
+closed_branch_tag_re: "(.+)(?<!newton)-eol"