www: remove npm package-lock.json for now (#556)

While the package lock is useful to consistently include the same
versions of each package, right now it causes too much noise with
dependabot, as new versions are released but with little or no impact on
this project because the web port is not yet usable (see #446 🕸️ Web
support)

www/.gitignore

@@ -1,2 +1,3 @@
 node_modules
 dist
+package-lock.json