support/scripts/pkg-stats: prefers stable version from release-monitoring.org

For example with libpng: 1.6.37 instead of 1.7.0beta89

Signed-off-by: Francois Perrad <francois.perrad@gadz.org>
[yann.morin.1998@free.fr: coalesce into a single line]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
(cherry picked from commit f7b0e086053644b29ec29fa775b7f0ffa0ba408a)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

support/scripts/pkg-stats

@@ -473,7 +473,7 @@ async def check_package_get_latest_version_by_distro(session, pkg, retry=True):
                 return False
 
             data = await resp.json()
-            version = data['version'] if 'version' in data else None
+            version = data['stable_versions'][0] if 'stable_versions' in data else data['version'] if 'version' in data else None
             check_package_latest_version_set_status(pkg,
                                                     RM_API_STATUS_FOUND_BY_DISTRO,
                                                     version,