Fix left arrow being split into less-than and negative-sign - #2086

error: unexpected token: `<-`
 --> src/main.rs:1:20
  |
1 | const _: bool = -3 <-1;
  |                    ^^
  |
help: if you meant to write a comparison against a negative value, add a space in between `<` and `-`
  |
1 | const _: bool = -3 < -1;
  |                     +