Fix tiny bug

revert the default target back to wasm32-wasi. set target to wasm32-unknown-unknown if the crate type is clib and version of rustc is 1.51.0 or higher

wasm32-unknown-unknown will be the default target. Use --wasi to compile to wasm32-wasi.

There is an installation issue reported in #11 (comment)
It seems that these binaries need to be rebuilt and then re-uploaded here.

For example:
a) the name of the compressed binary must be rustwasmc instead of ssvmup (so that the URL for the fetch in the installer is correct)
b) the actual root dir of the repo (once uncompressed) needs to be rustwasmc instead of ssvmup or the installer will break.