Replace double quotes with single quotes for literal string to conform to SQLite syntax

closes #301

As per the information provided in SQLite documentation, string literals in SQLite should use single quotes as the standard syntax. Prior to version 3.41.0 (2023-02-21), SQLite accepted double-quoted string literals due to compatibility with MySQL 3.x syntax. However, starting with version 3.41.0, SQLite no longer allows double quotes for string literals by default. Instead, string literals enclosed in double quotes are now interpreted as column names.

This merge request updates the code by replacing all double quotes around string literals with single quotes, ensuring compatibility with SQLite 3.29.0 and later versions, and preventing potential errors.

Notice that the decision to deprecate single-quote strings wasn't enforced until SQLite 3.49.