Updating Wake example to use new 'pin!' macro

[madsravn]

Updating the example for the Wake trait to use pin! macro instead of Box::pin.
#109965

[rustbot]

r? @Mark-Simulacrum

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[rustbot]

Hey! It looks like you've submitted a new PR for the library teams!

If this PR contains changes to any rust-lang/rust public library APIs then please comment with @rustbot label +T-libs-api -T-libs to tag it appropriately. If this PR contains changes to any unstable APIs please edit the PR description to add a link to the relevant API Change Proposal or create one if you haven't already. If you're unsure where your change falls no worries, just leave it as is and the reviewer will take a look and make a decision to forward on if necessary.

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[Mark-Simulacrum]

@bors r+ rollup

[bors]

📌 Commit 4698b9f has been approved by Mark-Simulacrum

It is now in the queue for this repository.