Security upgrade node from boron to 14.21.3

[cloudgeek7]

Changes included in this PR

• 03-path-application-development/303-app-update/images/app-v1/Dockerfile

We recommend upgrading to node:14.21.3, as this image has only 388 known vulnerabilities. To do this, merge this pull request, then verify your application still works as expected.

Some of the most important vulnerabilities in your base image include:

Severity	Priority Score / 1000	Issue	Exploit Maturity
Critical	714	NULL Pointer DereferenceSNYK-DEBIAN9-IMAGEMAGICK-401678	No Known Exploit
Critical	714	Out-of-bounds ReadSNYK-DEBIAN9-LIBXML2-429367	No Known Exploit
Critical	714	Integer Overflow or WraparoundSNYK-DEBIAN9-MERCURIAL-311063	No Known Exploit
Critical	714	OS Command InjectionSNYK-DEBIAN9-MERCURIAL-311070	No Known Exploit
Critical	714	Incorrect Permission Assignment for Critical ResourceSNYK-DEBIAN9-MERCURIAL-311113	No Known Exploit