Remove Expr::new (#917)

#897 (comment)

> I'm considering removing Expr::new, since we already have Expr::from.
> As @Expurple mentioned here, I checked my codebase and found that
using Expr::from makes the intent clearer. Moreover, accepting
Into<Self> in the new method is not idiomatic in Rust.

Author: Huliiiiii

src/expr.rs

@@ -1543,10 +1543,6 @@ where
 }
 
 impl Expr {
-    pub fn new(expr: impl Into<Self>) -> Self {
-        expr.into()
-    }
-
     #[deprecated(since = "0.29.0", note = "Please use the [`Asterisk`]")]
     pub fn asterisk() -> Self {
         Self::col(Asterisk)