Fix negative number parsing in fixed-point-wasm (#1469)

* Fix sign removal in `Numberish` parsing.

* Rebuild crate

* Add changeset

Author: ryangoree

.changeset/clever-avocados-breathe.md

@@ -0,0 +1,5 @@
+---
+"@delvtech/fixed-point-wasm": patch
+---
+
+Fix negative number parsing for strings and `parseFixed`

crates/fixed-point-wasm/src/lib.rs

@@ -452,11 +452,11 @@ impl TryFrom<Numberish> for FixedPoint<I256> {
                     .replace_all(",", "");
                 let mut sign = 1;
                 if s.starts_with("-", 0) {
-                    s = s.slice(0, s.length());
+                    s = s.slice(1, s.length());
                     sign = -1;
                 };
                 if s.starts_with("+", 0) {
-                    s = s.slice(0, s.length());
+                    s = s.slice(1, s.length());
                 };
                 if s.starts_with("0x", 0) || s.starts_with("0b", 0) || s.starts_with("0o", 0) {
                     let int = s.to_i256()? * I256::from(sign);