Support wasmtime 4.0

[bajtos]

When adding wasi-experimental-http-wasmtime to a project using wasmtime version 4.0.0 (latest at the time of writing), cargo complains about versioning conflicts.

      Adding wasi-experimental-http-wasmtime v0.10.0 to dependencies.
error: failed to select a version for `wasi-common`.
    ... required by package `wasi-experimental-http-wasmtime v0.10.0`
    ... which satisfies dependency `wasi-experimental-http-wasmtime = "^0.10.0"` of package `demo v0.1.0 (/Users/bajtos/src/pl/runtime-poc/wasmtime)`
versions that meet the requirements `^0.35` are: 0.35.3, 0.35.2, 0.35.1, 0.35.0

the package `wasi-common` links to the native library `wasi-common-19`, but it conflicts with a previous package which links to `wasi-common-19` as well:
package `wasi-common v4.0.0`
    ... which satisfies dependency `wasi-common = "=4.0.0"` of package `wasi-cap-std-sync v4.0.0`
    ... which satisfies dependency `wasi-cap-std-sync = "=4.0.0"` of package `wasi-tokio v4.0.0`
    ... which satisfies dependency `wasi-tokio = "=4.0.0"` of package `wasmtime-wasi v4.0.0`
    ... which satisfies dependency `wasmtime-wasi = "^4.0.0"` of package `demo v0.1.0 (/Users/bajtos/src/pl/runtime-poc/wasmtime)`
Only one package in the dependency graph may specify the same links value. This helps ensure that only one copy of a native library is linked in the final binary. Try to adjust your dependencies so that only one package uses the links ='wasi-common' value. For more information, see https://doc.rust-lang.org/cargo/reference/resolver.html#links.

FWIW, downgrading my project to wasmtime version 0.35 allowed me to install wasi-experimental-http-wasmtime.