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_python_ast/src/identifier.rs

@@ -207,7 +207,7 @@ impl<'a> IdentifierTokenizer<'a> {
                 _ => {
                     // Nothing to do.
                 }
-            };
+            }
         }
 
         None

crates/ruff_python_ast/src/node.rs

@@ -322,10 +322,10 @@ impl ast::StmtRaise {
 
         if let Some(expr) = exc {
             visitor.visit_expr(expr);
-        };
+        }
         if let Some(expr) = cause {
             visitor.visit_expr(expr);
-        };
+        }
     }
 }
 

crates/ruff_python_ast/src/nodes.rs

@@ -1522,7 +1522,7 @@ impl BytesLiteralFlags {
                 self.0
                     .set(BytesLiteralFlagsInner::R_PREFIX_LOWER, !uppercase_r);
             }
-        };
+        }
         self
     }
 
@@ -1749,7 +1749,7 @@ impl AnyStringFlags {
         match quotes {
             Quote::Double => self.0 |= AnyStringFlagsInner::DOUBLE,
             Quote::Single => self.0 -= AnyStringFlagsInner::DOUBLE,
-        };
+        }
         self
     }
 

crates/ruff_python_ast/src/visitor.rs

@@ -276,10 +276,10 @@ pub fn walk_stmt<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, stmt: &'a Stmt) {
         }) => {
             if let Some(expr) = exc {
                 visitor.visit_expr(expr);
-            };
+            }
             if let Some(expr) = cause {
                 visitor.visit_expr(expr);
-            };
+            }
         }
         Stmt::Try(ast::StmtTry {
             body,

crates/ruff_python_ast/src/visitor/transformer.rs

@@ -263,10 +263,10 @@ pub fn walk_stmt<V: Transformer + ?Sized>(visitor: &V, stmt: &mut Stmt) {
         }) => {
             if let Some(expr) = exc {
                 visitor.visit_expr(expr);
-            };
+            }
             if let Some(expr) = cause {
                 visitor.visit_expr(expr);
-            };
+            }
         }
         Stmt::Try(ast::StmtTry {
             body,