AppStream metadata: Fix release date for 1.8.6

Author: junrrein

data/com.github.junrrein.PDFSlicer.appdata.xml.in

@@ -32,7 +32,7 @@
 		</screenshot>
 	</screenshots>
 	<releases>
-		<release version="1.8.6" date="2020-11-25">
+		<release version="1.8.6" date="2020-11-26">
 			<description>
 				<p>Most of the improvements in this release were made by contributors. Thanks a lot!</p>
 				<ul>