Sets version to 19.0 for the Potassium release.

ALL_VERSIONS

 Version number			Date of release		Notes
 ==============			===============		=====
+19.0 (Potassium)                2019, June 21
 18.0 (Argon)                    2018, November 29
 Chlorine-20180502               2018, July 06           Bug fixed
 Chlorine-20180501               2018, June 01

VERSION

-19.0-beta2
\ No newline at end of file
+19.0
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opam/opam

 opam-version: "2.0"
 name: "frama-c"
 synopsis: "Platform dedicated to the analysis of source code written in C"
-version: "19.0.beta2"
+version: "19.0"
 maintainer: "francois.bobot@cea.fr"
 authors: [
   "Michele Alberti"