Upgrade to Rust 1.86 and bump MSRV to 1.84 (#17171)

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## Summary

I decided to disable the new
[`needless_continue`](https://rust-lang.github.io/rust-clippy/master/index.html#needless_continue)
rule because I often found the explicit `continue` more readable over an
empty block or having to invert the condition of an other branch.


## Test Plan

`cargo test`

---------

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

crates/ruff_annotate_snippets/src/renderer/display_list.rs

@@ -315,7 +315,7 @@ impl DisplaySet<'_> {
                         None => {
                             buffer.putc(line_offset, lineno_width + 1, '|', *lineno_color);
                         }
-                    };
+                    }
                 }
                 if let DisplaySourceLine::Content { text, .. } = line {
                     // The width of the line number, a space, pipe, and a space
@@ -1753,7 +1753,7 @@ fn format_inline_marks(
             DisplayMarkType::AnnotationThrough(depth) => {
                 buf.putc(line, 3 + lineno_width + depth, '|', *annotation_style);
             }
-        };
+        }
     }
     Ok(())
 }