Update askama requirement from 0.14.0 to 0.15.0

Updates the requirements on [askama](https://github.com/askama-rs/askama) to permit the latest version.
- [Release notes](https://github.com/askama-rs/askama/releases)
- [Commits](askama-rs/askama@v0.14.0...v0.15.0)

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

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

Author: dependabot[bot]

plotly/Cargo.toml

@@ -56,7 +56,7 @@ kaleido_download = ["plotly_kaleido/download"]
 
 
 [dependencies]
-askama = { version = "0.14.0", features = ["serde_json"] }
+askama = { version = "0.15.0", features = ["serde_json"] }
 dyn-clone = "1"
 erased-serde = "0.4"
 image = { version = "0.25", optional = true }