.github: update actions (#76)

Author: Erisa

.github/workflows/nix.yaml

@@ -12,7 +12,7 @@ jobs:
       packages: write
     steps:
     - uses: actions/checkout@v4
-    - uses: cachix/install-nix-action@v27
+    - uses: cachix/install-nix-action@v30
       with:
         github_access_token: ${{ secrets.GITHUB_TOKEN }}
     - name: "Basic CLI and web build"
@@ -37,7 +37,7 @@ jobs:
         nix build .#portable-service
         mkdir -p var
         cp ./result/*.raw ./var
-    - uses: actions/upload-artifact@v3
+    - uses: actions/upload-artifact@v4
       with:
         name: portable-service
         path: ./var/*.raw