fix: bump serde-wasm-bindgen, js-sys to fix broken compile

[SuperFluffy]

Fixes failing compilation of wasm-bindgest-test by bumping serde-wasm-bindgen@v0.6.5 and js-sys@=v0.3.70 (see compilation error at the bottom of these patch notes).

• Referenced an issue explaining the need for the change
• Updated all relevant documentation in docs
• Updated all code comments where relevant
• Wrote tests (formerly broken compiles work now)
• Added entry in .changelog/

Compilation errors seen in CI:

error[E0152]: found duplicate lang item `panic_impl`
   --> /home/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/wasm-bindgen-test-0.3.49/src/rt/mod.rs:321:9
    |
321 | /         fn panic_handler(panic_info: &core::panic::PanicInfo<'_>) -> ! {
322 | |             panic_handling(panic_info.to_string());
323 | |             core::arch::wasm32::unreachable();
324 | |         }
    | |_________^
    |
    = note: the lang item is first defined in crate `std` (which `js_sys` depends on)
    = note: first definition in `std` loaded from /home/runner/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-unknown/lib/libstd-89e63d1941b447bf.rlib
    = note: second definition in the local crate (`wasm_bindgen_test`)

For more information about this error, try `rustc --explain E0152`.
error: could not compile `wasm-bindgen-test` (lib) due to 1 previous error
warning: build failed, waiting for other jobs to finish...
Error: Compilation of your program failed
Caused by: Compilation of your program failed
Caused by: failed to execute `cargo build`: exited with exit status: 101
  full command: cd "./light-client-js/" && "cargo" "build" "--tests" "--target" "wasm32-unknown-unknown"

[SuperFluffy]

Looks like CI failed due to a (potential) network error. I don't have permissions to kick the job to see if it's real.