Update scraper requirement from 0.20 to 0.21

Updates the requirements on [scraper](https://github.com/causal-agent/scraper) to permit the latest version.
- [Release notes](https://github.com/causal-agent/scraper/releases)
- [Commits](rust-scraper/scraper@v0.20.0...v0.21.0)

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

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

api/Cargo.toml

@@ -23,7 +23,7 @@ log.workspace = true
 opml.workspace = true
 rayon = "1.5"
 ring.workspace = true
-scraper = "0.20"
+scraper = "0.21"
 serde.workspace = true
 serde_json.workspace = true
 sha2.workspace = true