Relax wat version requirement

[andreiltd]

I want to update the wasmer version to the latest release in https://github.com/containerd/runwasi, but cargo fails to resolve dependencies due to overly restrictive version requirements for the wat crate. For example

error: failed to select a version for `wat`.
    ... required by package `wasmtime v26.0.1`
    ... which satisfies dependency `wasmtime = "^26.0.1"` of package `containerd-shim-benchmarks v0.4.0
versions that meet the requirements `^1.218.0` are: 1.219.1, 1.220.0, 1.219.0, 1.218.0

all possible versions conflict with previously selected packages.

  previously selected package `wat v1.216.0`
    ... which satisfies dependency `wat = "=1.216.0"` of package `wasmer v5.0.1`
    ... which satisfies dependency `wasmer = "^5.0.1"` of package `containerd-shim-wasmer v0.5.0

Could we relax the strict version requirement?

[xdoardo]

Thanks!