Handle parentheses when formatting slice expressions

**Summary** Fix the formatter crash with `x[(1) :: ]` and related code.

**Problem** For assigning comments in slices in subscripts, we need to find the positions of the colons to assign comments before and after the colon to the respective lower/upper/step node (or dangling in that section). Formatting `x[(1) :: ]` was broken because we were looking for a `:` after the `1` but didn't consider that there could be a `)` outside the range of the lower node, which contains just the `1` and no optional parentheses.

**Solution** Use the simple tokenizer directly and skip all closing parentheses.

**Test Plan** I added regression tests.

Closes #5733

crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/slice.py

@@ -83,3 +83,8 @@ def a():
 
 # Regression test for https://github.com/astral-sh/ruff/issues/5605
 f = "f"[:,]
+
+# Regression test for https://github.com/astral-sh/ruff/issues/5733
+g1 = "g"[(1):(2)]
+g2 = "g"[(1):(2):(3)]
+

crates/ruff_python_formatter/src/expression/expr_slice.rs

@@ -5,7 +5,7 @@ use rustpython_parser::ast::{Expr, Ranged};
 use ruff_formatter::prelude::{hard_line_break, line_suffix_boundary, space, text};
 use ruff_formatter::{write, Buffer, Format, FormatError, FormatResult};
 use ruff_python_ast::node::{AnyNodeRef, AstNode};
-use ruff_python_whitespace::{first_non_trivia_token, Token, TokenKind};
+use ruff_python_whitespace::{SimpleTokenizer, Token, TokenKind};
 
 use crate::comments::{dangling_comments, SourceComment};
 use crate::context::PyFormatContext;
@@ -162,10 +162,12 @@ pub(crate) fn find_colons(
     let after_lower = lower
         .as_ref()
         .map_or(range.start(), |lower| lower.range().end());
-    let first_colon =
-        first_non_trivia_token(after_lower, contents).ok_or(FormatError::SyntaxError {
-            message: "Din't find any token for slice first colon",
-        })?;
+    let mut tokens = SimpleTokenizer::new(contents, TextRange::new(after_lower, range.end()))
+        .skip_trivia()
+        .skip_while(|token| token.kind == TokenKind::RParen);
+    let first_colon = tokens.next().ok_or(FormatError::SyntaxError {
+        message: "Din't find any token for slice first colon",
+    })?;
     if first_colon.kind != TokenKind::Colon {
         return Err(FormatError::SyntaxError {
             message: "slice first colon token was not a colon",
@@ -175,17 +177,16 @@ pub(crate) fn find_colons(
     let after_upper = upper
         .as_ref()
         .map_or(first_colon.end(), |upper| upper.range().end());
-    // At least the closing bracket must exist, so there must be a token there
-    let next_token =
-        first_non_trivia_token(after_upper, contents).ok_or(FormatError::SyntaxError {
-            message: "Din't find any token for slice second colon",
-        })?;
-    let second_colon = if next_token.kind == TokenKind::Colon {
-        debug_assert!(
-            next_token.range.start() < range.end(),
-            "The next token in a slice must either be a colon or the closing bracket"
-        );
-        Some(next_token)
+    let mut tokens = SimpleTokenizer::new(contents, TextRange::new(after_upper, range.end()))
+        .skip_trivia()
+        .skip_while(|token| token.kind == TokenKind::RParen);
+    let second_colon = if let Some(token) = tokens.next() {
+        if token.kind != TokenKind::Colon {
+            return Err(FormatError::SyntaxError {
+                message: "Expected a colon for the second colon token",
+            });
+        }
+        Some(token)
     } else {
         None
     };