Bump log4js from 6.3.0 to 6.4.0 in /1-Authentication/1-sign-in/SPA

Bumps [log4js](https://github.com/log4js-node/log4js-node) from 6.3.0 to 6.4.0. - [Release notes](https://github.com/log4js-node/log4js-node/releases) - [Changelog](https://github.com/log4js-node/log4js-node/blob/master/CHANGELOG.md) - [Commits](log4js-node/log4js-node@v6.3.0...v6.4.0) --- updated-dependencies: - dependency-name: log4js dependency-type: indirect ... Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]