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

<!--
Thank you for contributing to Ruff! To help us out with reviewing,
please consider the following:

- Does this pull request include a summary of the change? (See below.)
- Does this pull request include a descriptive title?
- Does this pull request include references to any relevant issues?
-->

## 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 https://github.com/astral-sh/ruff/pull/6873

## Test Plan

<!-- How was it tested? -->

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",