Add express to dependencies; Update follow-redirects to newest version (

#225)

This is the second part of solving:

- #224 

The first part is WordPress/wordpress-playground#1218. (php-wasm/node:
Update express to newest version, and move it to devDependencies)

## Why?

The first part of the solution is in the Playground project, which
updates `express` and moves it to `devDependencies` since it's only used
for tests in that project.

As a result, `express` will no longer be installed when `@php-wasm/node`
is installed. So `wp-now` needs to declare `express` as a dependency.

## How?

- Add `express` to `dependencies`
- Update `follow-redirects` to newest `1.15.6`

These together with WordPress/wordpress-playground#1218 will resolve the
original issue #224, which should eliminate all npm audit warnings.

## Testing Instructions

Currently `npm run test` fails with an unrelated issue, as can be seen
in another PR's CI test run.
https://github.com/WordPress/playground-tools/actions/runs/8616282863/job/23614052137?pr=223#step:4:49
("RuntimeError: memory access out of bounds") That seems have been
caused by commit
[133029c](133029c).

package.json

@@ -43,9 +43,10 @@
 		"compressible": "2.0.18",
 		"compression": "1.7.4",
 		"copy-webpack-plugin": "11.0.0",
+		"express": "4.19.2",
 		"express-fileupload": "1.4.0",
 		"file-saver": "^2.0.5",
-		"follow-redirects": "1.15.2",
+		"follow-redirects": "1.15.6",
 		"fs-extra": "11.1.1",
 		"hpagent": "1.2.0",
 		"react": "^18.2.0",