Update itertools requirement from >=0.10, <0.15 to >=0.10, <0.16

Updates the requirements on [itertools](https://github.com/rust-itertools/itertools) to permit the latest version.
- [Changelog](https://github.com/rust-itertools/itertools/blob/master/CHANGELOG.md)
- [Commits](rust-itertools/itertools@v0.10.0...v0.15.0)

---
updated-dependencies:
- dependency-name: itertools
  dependency-version: 0.15.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

plotly/Cargo.toml

@@ -85,7 +85,7 @@ web-sys = { version = "0.3.77", features = [
 [dev-dependencies]
 csv = "1.1"
 image = "0.25"
-itertools = ">=0.10, <0.15"
+itertools = ">=0.10, <0.16"
 itertools-num = "0.1"
 ndarray = "0.17"
 plotly_static = { path = "../plotly_static" }