debian/changelog: UNRELEASED => experimental

Gbp-Dch: Ignore

debian/changelog

-openexr (2.3.0-4) UNRELEASED; urgency=medium
+openexr (2.3.0-4) experimental; urgency=medium
 
   * debian/control: SONAME bump 23 -> 24 to reflect libtool numbering
   * debian/: filenames adapted to SONAME bump
   * debian/control: S-V bump 4.2.1 -> 4.3.0 (no changes needed)
   * debian/control: bump dependency on ilmbase to "-3" revision
 
- -- Matteo F. Vescovi <mfv@debian.org>  Mon, 31 Dec 2018 15:30:38 +0100
+ -- Matteo F. Vescovi <mfv@debian.org>  Mon, 31 Dec 2018 15:37:38 +0100
 
 openexr (2.3.0-3) experimental; urgency=medium