Fixed #26613 -- Made sqlite3 optional in SchemaEditor.quote_value().

        # The backend "mostly works" without this function and there are use

        # cases for compiling Python without the sqlite3 libraries (e.g.

        # security hardening).

        import sqlite3

        try:

            import sqlite3

            value = sqlite3.adapt(value)

        except ImportError:

            pass

        except sqlite3.ProgrammingError:

            pass

        # Manual emulation of SQLite parameter quoting