Backslashes stored incorrectly in __db_version__

[dsinn]

The backslashes get unescaped twice before entering the database.

For example, if I have
INSERT INTOtableNameVALUES('\\\\my\\\\namespace');
then it will enter db_version.sql_up or sql_down as
INSERT INTOtableNameVALUES('\my\namespace');

This is especially problematic if backslashes appear in sql_down, as running with --force-files will cause different queries to be executed even when there are no changes to the migration file.