ci: remove actions-rs use nix to check

.github/workflows/build.yml

@@ -72,16 +72,15 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        toolchain: [ nightly, beta, stable, 1.75.0 ]
+        toolchain: [ nightly, beta, stable, msrv ]
     steps:
-      - uses: actions/checkout@v2
-      - name: Install rust ${{ matrix.toolchain }}
-        uses: actions-rs/toolchain@v1
-        with:
-          toolchain: ${{ matrix.toolchain }}
-          override: true
-      - name: All features
-        uses: actions-rs/cargo@v1
-        with:
-          command: check
-          args: --workspace --all-targets --all-features
+      - name: checkout
+        uses: actions/checkout@v4
+      - name: Install Nix
+        uses: DeterminateSystems/nix-installer-action@v5
+      - name: Nix Cache
+        uses: DeterminateSystems/magic-nix-cache-action@v2
+      - name: Rust Cache
+        uses: Swatinem/rust-cache@v2
+      - name: Check rgb-core
+        run: nix develop ".#${{ matrix.toolchain }}" -c cargo check --workspace --all-targets --all-features

flake.nix

@@ -0,0 +1,54 @@
+{
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    rust-overlay = {
+      url = "github:oxalica/rust-overlay";
+      inputs.nixpkgs.follows = "nixpkgs";
+      inputs.flake-utils.follows = "flake-utils";
+    };
+
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, rust-overlay, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        overlays = [ (import rust-overlay) ];
+        pkgs = import nixpkgs {
+          inherit system overlays;
+        };
+
+        cargoToml = builtins.fromTOML (builtins.readFile ./Cargo.toml);
+      in
+      with pkgs;
+      {
+        devShells = rec {
+          default = msrv;
+
+          msrv = mkShell {
+            buildInputs = [
+              rust-bin.stable."${cargoToml.package."rust-version"}".default
+            ];
+          };
+
+          stable = mkShell {
+            buildInputs = [
+              rust-bin.stable.latest.default
+            ];
+          };
+
+          beta = mkShell {
+            buildInputs = [
+              rust-bin.beta.latest.default
+            ];
+          };
+
+          nightly = mkShell {
+            buildInputs = [
+              rust-bin.nightly.latest.default
+            ];
+          };
+        };
+      }
+    );
+}