memory (sqlite): cast timestamp_start filter to float instead of int

sat/memory/sqlite.py

@@ -594,7 +594,7 @@ class SqliteStorage(object):
         if filters:
             if u'timestamp_start' in filters:
                 query_parts.append(u"AND timestamp>= ?")
-                values.append(int(filters[u'timestamp_start']))
+                values.append(float(filters[u'timestamp_start']))
             if u'body' in filters:
                 # TODO: use REGEXP (function to be defined) instead of GLOB: https://www.sqlite.org/lang_expr.html
                 query_parts.append(u"AND message LIKE ?")