## Summary

This PR fixes a bug in the lexer specifically around line continuation
character at end of file.

The reason this was occurring is because the lexer wouldn't check for
EOL _after_ consuming the escaped newline but only if the EOL was right
after the line continuation character.

fixes: #17398 

## Test Plan

Add tests for the scenarios where this should occur mainly (a) when the
state is `AfterNewline` and (b) when the state is `Other`.

* main: (44 commits)
  [`airflow`] Extend `AIR311` rules (#17422)
  [red-knot] simplify union size limit handling (#17429)
  [`airflow`] Extract `AIR311` from `AIR301` rules (`AIR301`, `AIR311`) (#17310)
  [red-knot] set a size limit on unions of literals (#17419)
  [red-knot] make large-union benchmark slow again (#17418)
  [red-knot] optimize building large unions of literals (#17403)
  [red-knot] Fix comments in type_api.md (#17425)
  [red-knot] Do not assume that `x != 0` if `x` inhabits `~Literal[0]` (#17370)
  [red-knot] make large-union benchmark more challenging (#17416)
  [red-knot] Acknowledge that `T & anything` is assignable to `T` (#17413)
  Update Rust crate clap to v4.5.36 (#17381)
  Raise syntax error when `\` is at end of file (#17409)
  [red-knot] Add regression tests for narrowing constraints cycles (#17408)
  [red-knot] Add some knowledge of `__all__` to `*`-import machinery (#17373)
  Update taiki-e/install-action digest to be7c31b (#17379)
  Update Rust crate mimalloc to v0.1.46 (#17382)
  Update PyO3/maturin-action action to v1.49.1 (#17384)
  Update Rust crate anyhow to v1.0.98 (#17380)
  dependencies: switch from `chrono` to `jiff`
  Update Rust crate bstr to v1.12.0 (#17385)
  ...