update web-sys & wasm

[bircni]

This PR updates web-sys & wasm to the newest version.

(this was already part of the POC #4954 )

• Closes https://github.com/emilk/egui/issues/4961
• Closes https://github.com/emilk/egui/issues/4958
• [x] I have followed the instructions in the PR template