Updated debian changelog for version 6.3.1

debian/changelog

+swh-model (6.3.1-1~swh1) unstable-swh; urgency=medium
+
+  * New upstream release 6.3.1     - (tagged by Valentin Lorentz
+    <vlorentz@softwareheritage.org> on 2022-07-20 11:35:17 +0200)
+  * Upstream changes:     - v6.3.1     - * hypothesis_strategies:
+    Prevent generation of invalid 'microseconds' values
+
+ -- Software Heritage autobuilder (on jenkins-debian1) <jenkins@jenkins-debian1.internal.softwareheritage.org>  Wed, 20 Jul 2022 09:39:38 +0000
+
 swh-model (6.3.0-1~swh1) unstable-swh; urgency=medium
 
   * New upstream release 6.3.0     - (tagged by Valentin Lorentz