get wasm demo working with wasm_exec.js version go1.21.0

[boddumanohar]

Currently wasm demo uses wasm_exec.js version go1.21

https://github.com/0chain/gosdk/blob/acc4fcd55ab597f547c422eb3ed1655d71395109/wasmsdk/demo/index.html#L6

But using this version results in this error

To reproduce this:

1. Start the wasm demo:

   
   # generate wasm sdk
   make wasm-build
   cp ./zcn.wasm ./wasmsdk/demo/zcn.wasm

go to wasm demo folder

cd wasmsdk/demo go run main.go

2. Open the URL: `http://127.0.0.1:8080/` in browser and check the console tab. You can find this error. 

To fix this, Currently, I have to use version `1.18.5` and that will work as expected. 

We should understand why our wasm binary doesn't work with go1.21

[sculptex]

The wasm_exec.js version has to match version of go that the wasm target is built with

[boddumanohar]

the go version used to build the wasm binary and wasm_exec.js version. Both of them should always match. Thanks for clarifying @sculptex 👍