crane+flakify to fix serde_derive

new serde breaks with crate2nix: serde-rs/serde#2538

.github/workflows/build.yml

@@ -6,7 +6,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/[email protected]
-    - uses: cachix/install-nix-action@v12
+    - uses: cachix/install-nix-action@v22
       with:
         nix_path: nixpkgs=channel:nixos-unstable
-    - run: nix-build Cargo.nix
+    - run: nix build

.github/workflows/bump.yml

@@ -11,12 +11,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/[email protected]
-    - uses: cachix/install-nix-action@v12
+    - uses: cachix/install-nix-action@v22
     - name: Update dependencies
       run: |
-        nix-shell --run "niv update"
-        nix-shell --run "cargo update"
-        nix-shell --run "crate2nix generate -n '(import ./nix/sources.nix).nixpkgs' -f Cargo.toml"
+        nix flake update --commit-lock-file
     - name: Create pull request
       id: pr
       uses: peter-evans/[email protected]