test: migrate weak_dep_features, workspaces and yank to snapbox

[eth3lbert]

What does this PR try to resolve?

Part of #14039.

Migrate following to snapbox:

• tests/testsuite/weak_dep_features.rs
• tests/testsuite/workspaces.rs
• tests/testsuite/yank.rs

[rustbot]

r? @ehuss

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[eth3lbert]

Rebased and feedback addressed!

Additionally, I've replaced an empty str![] with "".

diff --git a/tests/testsuite/weak_dep_features.rs b/tests/testsuite/weak_dep_features.rs
index f5d2e18e5..da281bfe3 100644
--- a/tests/testsuite/weak_dep_features.rs
+++ b/tests/testsuite/weak_dep_features.rs
@@ -517,7 +517,7 @@ foo v0.1.0 ([ROOT]/foo)
     // This is a little strange in that it produces no output.
     // Maybe `cargo tree` should print a note about why?
     p.cargo("tree -e features -i bar --features bar?/feat")
-        .with_stdout_data(str![])
+        .with_stdout_data("")
         .run();
 
     p.cargo("tree -e features -i bar --features bar?/feat,bar")

Thanks for the review! :)

[epage]

@bors r+

[bors]

📌 Commit e3ea0aa has been approved by epage

It is now in the queue for this repository.

[bors]

⌛ Testing commit e3ea0aa with merge bc89bff...

[bors]

☀️ Test successful - checks-actions
Approved by: epage
Pushing bc89bff to master...