Fix the fmt clippy fail

[devigned]

The error below was failing in the build for PR #67.

Checking containerd-shim-slight-v1 v0.1.0 (/home/runner/work/containerd-wasm-shims/containerd-wasm-shims/containerd-shim-slight-v1)
[943](https://github.com/deislabs/containerd-wasm-shims/actions/runs/4073348292/jobs/7028521089#step:5:944)
error: variables can be used directly in the `format!` string
[944](https://github.com/deislabs/containerd-wasm-shims/actions/runs/4073348292/jobs/7028521089#step:5:945)
  --> src/main.rs:37:38
[945](https://github.com/deislabs/containerd-wasm-shims/actions/runs/4073348292/jobs/7028521089#step:5:946)
   |
[946](https://github.com/deislabs/containerd-wasm-shims/actions/runs/4073348292/jobs/7028521089#step:5:947)
37 |         .map_err(|err| Error::Others(format!("could not canonicalize rootfs: {}", err)))?;
[947](https://github.com/deislabs/containerd-wasm-shims/actions/runs/4073348292/jobs/7028521089#step:5:948)
   |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[948](https://github.com/deislabs/containerd-wasm-shims/actions/runs/4073348292/jobs/7028521089#step:5:949)
   |
[949](https://github.com/deislabs/containerd-wasm-shims/actions/runs/4073348292/jobs/7028521089#step:5:950)
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args
[950](https://github.com/deislabs/containerd-wasm-shims/actions/runs/4073348292/jobs/7028521089#step:5:951)
   = note: `-D clippy::uninlined-format-args` implied by `-D warnings`
[951](https://github.com/deislabs/containerd-wasm-shims/actions/runs/4073348292/jobs/7028521089#step:5:952)
help: change this to
[952](https://github.com/deislabs/containerd-wasm-shims/actions/runs/4073348292/jobs/7028521089#step:5:953)
   |
[953](https://github.com/deislabs/containerd-wasm-shims/actions/runs/4073348292/jobs/7028521089#step:5:954)
37 -         .map_err(|err| Error::Others(format!("could not canonicalize rootfs: {}", err)))?;
[954](https://github.com/deislabs/containerd-wasm-shims/actions/runs/4073348292/jobs/7028521089#step:5:955)
37 +         .map_err(|err| Error::Others(format!("could not canonicalize rootfs: {err}")))?;

[rumpl]

It's funny because I have the same clippy errors on another PR in youki, did clippy change something recently?