debian/changelog: UNRELEASED => experimental

Gbp-Dch: Ignore

debian/changelog

-openexr (2.5.2-1) UNRELEASED; urgency=medium
+openexr (2.5.2-1) experimental; urgency=medium
 
   * New upstream release
 
- -- Matteo F. Vescovi <mfv@debian.org>  Thu, 06 Aug 2020 17:37:50 +0200
+ -- Matteo F. Vescovi <mfv@debian.org>  Thu, 06 Aug 2020 17:38:22 +0200
 
 openexr (2.5.1-2) experimental; urgency=medium