Revert "ci: Freeze rustc for nightly web builds to 1.81.0"

This reverts commit c8ded2e.

Author: torokati44

.github/workflows/release_nightly.yml

@@ -332,9 +332,9 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Install Rust toolchain
-        uses: dtolnay/rust-toolchain@master
+        uses: dtolnay/rust-toolchain@stable
         with:
-          toolchain: 1.81.0
+          toolchain: stable
           targets: wasm32-unknown-unknown
           components: rust-src