patch 9.0.1815: pango_coverage_unref() deprecated in pango > 1.51

Problem:  pango_coverage_unref() deprecated in pango > 1.51
Solution: use g_object_unref() instead

closes: #12942

Free PangoCoverage with g_object_unref for Pango >= 1.52

pango_coverage_unref was declared deprecated in Pango 1.52.0 in favor of
g_object_unref.  Adjust the call when building against a new enough
Pango to avoid the deprecation warning.

Signed-off-by: James McCoy <jamessan@jamessan.com>
Co-authored-by: James McCoy <jamessan@jamessan.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/version.c b/src/version.c
index ce28694..6d818ad 100644
--- a/src/version.c
+++ b/src/version.c
@@ -700,6 +700,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1815,
+/**/
     1814,
 /**/
     1813,