sqlite3: fix error when dropping db with system tables

In some cases SQLite creates new tables for internal use. The names
of these internal schema objects[0] always begin with `sqlite_` and are
not to be touched by applications.

Example case: if column declaration uses `AUTOINCREMENT` keyword, a new
column is created into table `sqlite_sequence` which can not be dropped.
Currently, `sqlite3.Drop()` resolves tables to be dropped by querying
table `sqlite_master` for all tables in the database. However, this query
also returns aforementioned `sqlite_sequence` table.

This commit adds a filter to the query resolving tables to be dropped.
Filter removes tables starting with `sqlite_` from the query results.

[0]: https://www.sqlite.org/fileformat2.html#intschema

database/sqlite3/sqlite3.go

@@ -134,7 +134,11 @@ func (m *Sqlite) Close() error {
 }
 
 func (m *Sqlite) Drop() (err error) {
-	query := `SELECT name FROM sqlite_master WHERE type = 'table';`
+	query := `
+		SELECT name FROM sqlite_master
+		WHERE type = 'table'
+		AND name NOT LIKE 'sqlite_%';`
+
 	tables, err := m.db.Query(query)
 	if err != nil {
 		return &database.Error{OrigErr: err, Query: []byte(query)}