⬆️ Update test-generator requirement from 0.2 to 0.3

Updates the requirements on [test-generator](https://github.com/frehberg/test-generator) to permit the latest version.
- [Release notes](https://github.com/frehberg/test-generator/releases)
- [Commits](https://github.com/frehberg/test-generator/commits)

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

Cargo.toml

@@ -23,7 +23,7 @@ reqwest = { version = "0.9", optional = true }
 failure = "0.1"
 
 [dev-dependencies]
-test-generator = "0.2"
+test-generator = "0.3"
 insta = "0.8"
 serde = { version = "1.0", features = [ "derive" ] }
 serde_json = "1.0"