Get cargo shear passing (#11392)

## Summary

Remove some unused dependencies, add a few ignores.

crates/ruff_python_formatter/Cargo.toml

@@ -11,7 +11,7 @@ repository = { workspace = true }
 license = { workspace = true }
 
 [lib]
-doctest= false
+doctest = false
 
 [dependencies]
 ruff_cache = { path = "../ruff_cache" }
@@ -49,6 +49,10 @@ serde = { workspace = true }
 serde_json = { workspace = true }
 similar = { workspace = true }
 
+[package.metadata.cargo-shear]
+# Used via `CacheKey` macro expansion.
+ignored = ["ruff_cache"]
+
 [[test]]
 name = "ruff_python_formatter_fixtures"
 path = "tests/fixtures.rs"