Switch packaging branch to debian/experimental

debian/changelog

@@ -1,3 +1,9 @@
+ostree (2019.3-2) UNRELEASED; urgency=medium
+
+  * Switch packaging branch to debian/experimental
+
+ -- Simon McVittie <smcv@debian.org>  Fri, 23 Aug 2019 09:03:04 +0100
+
 ostree (2019.3-1) unstable; urgency=medium
 
   * New upstream release

debian/gbp.conf

@@ -1,7 +1,7 @@
 [DEFAULT]
 pristine-tar = True
 compression = xz
-debian-branch = debian/master
+debian-branch = debian/experimental
 upstream-branch = upstream/latest
 patch-numbers = False
 upstream-vcs-tag = v%(version)s