Update unicode-width requirement from =0.1.12 to =0.1.13

Updates the requirements on [unicode-width](https://github.com/unicode-rs/unicode-width) to permit the latest version.
- [Commits](unicode-rs/unicode-width@v0.1.12...v0.1.13)

---
updated-dependencies:
- dependency-name: unicode-width
  dependency-type: direct:production
...

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data-url/Cargo.toml

@@ -17,7 +17,7 @@ alloc = []
 
 [dev-dependencies]
 tester = "0.9"
-unicode-width = "=0.1.12"
+unicode-width = "=0.1.13"
 serde = {version = "1.0", features = ["derive"]}
 serde_json = "1.0"