Update flume requirement from 0.10 to 0.11

Updates the requirements on [flume](https://github.com/zesterer/flume) to permit the latest version.
- [Changelog](https://github.com/zesterer/flume/blob/master/CHANGELOG.md)
- [Commits](https://github.com/zesterer/flume/commits)

---
updated-dependencies:
- dependency-name: flume
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

crossbeam-channel/benchmarks/Cargo.toml

@@ -10,7 +10,7 @@ bus = "2.3.0"
 crossbeam = { path = "../.." }
 crossbeam-channel = { path = ".." }
 crossbeam-deque = { path = "../../crossbeam-deque" }
-flume = "0.10"
+flume = "0.11"
 futures = { version = "0.3", features = ["thread-pool"] }
 lockfree = "0.5.1"
 mpmc = "0.1.6"