Remove unused synstructure dep

[clubby789]

synstructure is no longer used now that this crate was split out from rustc_macros

@rustbot label +C-cleanup

[rustbot]

r? @TaKO8Ki

(rustbot has picked a reviewer for you, use r? to override)

[rustbot]

These commits modify the Cargo.lock file. Random changes to Cargo.lock can be introduced when switching branches and rebasing PRs.
This was probably unintentional and should be reverted before this PR is merged.

If this was intentional then you can ignore this comment.

[Noratrieb]

r? Nilstrieb
whoops, r=me
@bors delegate+

[bors]

✌️ @clubby789 can now approve this pull request

[compiler-errors]

@bors r=Nilstrieb

[bors]

📌 Commit da5d01d has been approved by Nilstrieb

It is now in the queue for this repository.

[bors]

⌛ Testing commit da5d01d with merge 0af46a1...

[bors]

☀️ Test successful - checks-actions
Approved by: Nilstrieb
Pushing 0af46a1 to master...

[rust-timer]

Finished benchmarking commit (0af46a1): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	3.4%	[3.4%, 3.4%]	1
Regressions ❌ (secondary)	4.7%	[4.7%, 4.7%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	3.4%	[3.4%, 3.4%]	1

Cycles

This benchmark run did not return any relevant results for this metric.