Update patch status

* d/p/{debian/,}Use-Python-3-for-tests.patch:
  Mark patch as forwarded. It was previously considered
  Debian-specific, but upstream seem interested.
* Mark all other patches as applied upstream for 2018.3

debian/changelog

@@ -1,3 +1,12 @@
+ostree (2018.2-2) UNRELEASED; urgency=medium
+
+  * d/p/{debian/,}Use-Python-3-for-tests.patch:
+    Mark patch as forwarded. It was previously considered
+    Debian-specific, but upstream seem interested.
+  * Mark all other patches as applied upstream for 2018.3
+
+ -- Simon McVittie <smcv@debian.org>  Thu, 22 Feb 2018 22:55:11 +0000
+
 ostree (2018.2-1) unstable; urgency=medium
 
   * New upstream release