docs: release notes for the v20.3.19 release

[clydin]

Cherry-picks the changelog from the "20.3.x" branch to the next branch (main).

[gemini-code-assist]

Code Review

This pull request updates the CHANGELOG.md file with release notes for version 20.3.19. The new entry correctly documents the update of copy-webpack-plugin. I have included one minor suggestion to improve the formatting of the new table entry for consistency.

_{Note: Security Review has been skipped due to the limited scope of the PR.}

[gemini-code-assist]

There are some extra spaces in this table row. While this may not affect the final rendered output, removing them would improve the source file's consistency and readability.

Suggested change

	| [0299b4d1a](https://github.com/angular/angular-cli/commit/0299b4d1aca13f11a06e2e92c593fe3e20906d23) | fix | update copy-webpack-plugin to v14.0.0 |
	| [0299b4d1a](https://github.com/angular/angular-cli/commit/0299b4d1aca13f11a06e2e92c593fe3e20906d23) | fix | update copy-webpack-plugin to v14.0.0 |

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