Bumping the places DB schema version

This should have been bumped when the migration was added.  Not bumping
it means that nightly users aren't migrating their DBs, which is
breaking syncing.

components/places/src/db/schema.rs

@@ -11,7 +11,7 @@ use crate::types::SyncStatus;
 use rusqlite::Connection;
 use sql_support::ConnExt;
 
-pub const VERSION: u32 = 15;
+pub const VERSION: u32 = 16;
 
 // Shared schema and temp tables for the read-write and Sync connections.
 const CREATE_SHARED_SCHEMA_SQL: &str = include_str!("../../sql/create_shared_schema.sql");