No longer create longlines with edit-deliverables

That was a constant paper cut for me: every time someone uses
edit-deliverables it may result in release highlights being
reformatted to create lines over 80 char. You can see that
happening at:

https://review.openstack.org/#/c/650911/1/deliverables/rocky/cloudkitty.yaml

where it messes up perfectly-good yaml and turns it into 88-char-long
lines.

I experimented with various settings (you would think width=80 would
do, but no). Forcing dump width at 66 characters seems to produce the
desired results.

Change-Id: I83934a0f7d6eeaec47b5dcb1a6bfb8c53ed65799

openstack_releases/yamlutils.py

@@ -117,6 +117,7 @@ def dumps(obj):
                   indent=2,
                   default_flow_style=False,
                   line_break="\n",
+                  width=66,
                   Dumper=PrettySafeDumper,
                   allow_unicode=True)
     return buff.getvalue()