Promotion notation should support input syntax without the equal sign

[Rqnsom]

Currently the promotion notation is printed out in this format below:

• a8=Q
• axb1=Q

And that printout format is fine for now.
To generate Turn structs we use:

let a8_promotion = Turn::try_form("a8=Q");
let b1_promotion = Turn::try_form("axb1=Q");

What is not supported today, but should be supported in Turn::try_form function is the same promotion but also with this syntax:

let a8_promotion = Turn::try_form("a8Q");  // No equal sign
let b1_promotion = Turn::try_form("axb1Q");  // No equal sign

assert_eq!(Turn::try_form("a8Q"), Turn::try_form("a8=Q"));
assert!(Turn::try_form("axb1Q").is_ok());

Quote from chess.com

The official FIDE way to indicate a pawn promotion is the notation for the pawn move with the addition of the piece the pawn was promoted to at the end. If a pawn on the a-file promotes to a queen, the official FIDE notation would be a8Q. If a pawn on the f-file captures another piece on the e-file and promotes to a knight, fxe8N.