Add maximum length for line-length to JSON schema (#7412)

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## Summary

<!-- What's the purpose of the change? What does it do, and why? -->
Adds the maximum of 320 for the line-length setting to the JSON schema
for better integration with IDEs.

Related #6873

## Test Plan

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crates/ruff_workspace/src/options.rs

@@ -319,7 +319,8 @@ pub struct Options {
         "#
     )]
     /// The line length to use when enforcing long-lines violations (like
-    /// `E501`). Must be greater than `0`.
+    /// `E501`). Must be greater than `0` and less than or equal to `320`.
+    #[cfg_attr(feature = "schemars", schemars(range(min = 1, max = 320)))]
     pub line_length: Option<LineLength>,
     #[option(
         default = "4",