fix(tvm): dtype error on Electron example app

[khj809]

On Electron example app, there's intermittent error raised from tvm-ffi as below:

thread 'tokio-runtime-worker' (116479489) panicked at /Users/runner/.cargo/git/checkouts/tvm-runtime-rs-bb1fb69546d1a22f/d0edb6e/tvm-runtime/src/tensor_cache.rs:87:75:
called `Result::unwrap()` on an `Err` value: Traceback (most recent call last):

  File "src/ffi/dtype.cc", line 309, in DLDataType tvm::ffi::StringViewToDLDataType_(std::string_view)
ValueError: unknown dtype `float16`
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

which is fixed by apache/tvm-ffi#387.

This PR updates tvm-runtime-rs to brekkylab/tvm-runtime-rs@fe81eb3, which applies the above fix.

[khj809]

Waiting for apache/tvm-ffi#387 to be merged. I think it would be done shortly.