Add dev shell within the javascript ffi bindings test

Remove msrv rust toolchain env

Author: benalleng

.github/workflows/javascript.yml

@@ -8,12 +8,6 @@ on:
   pull_request:
     paths:
       - payjoin-ffi/**
-env:
-  # Override the value from the rust-toolchain file
-  # This is necessary because even though the correct toolchain
-  # is explicitly specified for the rust-toolchain action,
-  # rustup honors the rust-toolchain file over the default
-  RUSTUP_TOOLCHAIN: 1.85
 
 jobs:
   build-js-and-test:
@@ -29,22 +23,14 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
 
-      - name: Install Rust 1.85.0
-        uses: dtolnay/rust-toolchain@1.85.0
-
       - name: "Use cache"
         uses: Swatinem/rust-cache@v2
 
-      - name: Install Node
-        uses: actions/setup-node@v6
-
-      - name: Install llvm
-        if: matrix.os == 'macos-latest'
-        run: brew install llvm
+      - name: "Install nix"
+        uses: DeterminateSystems/determinate-nix-action@main
 
-      # 0.2.109+ requires rustc 1.88 (via time crate).
-      - name: Install wasm-bindgen
-        run: cargo install --locked wasm-bindgen-cli --version 0.2.108
+      - name: "Use nix cache"
+        uses: DeterminateSystems/magic-nix-cache-action@main
 
       - name: "Build and test"
-        run: bash ./contrib/test.sh
+        run: nix develop .#msrv -c ./contrib/test.sh