Add upload-artifacts action

Copied from https://github.com/input-output-hk/haskell-nix-example/blob/99a390674580c10f140dc4e2d5d0b889418b9d91/.github/workflows/upload-artifacts.yml

Author: hamishmack

.github/workflows/upload-artifacts.yml

@@ -0,0 +1,89 @@
+name: Wait for Hydra Build
+
+on:
+  push:
+    branches:
+      - main
+    tags:
+      - "v*.*"
+  pull_request:
+
+env:
+  FLAKE_REF: github:${{ github.repository }}?ref=${{ github.head_ref || github.ref }}
+  GH_TOKEN: ${{ github.token }}
+
+jobs:
+  wait-for-hydra:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install Nix with good defaults
+        uses: input-output-hk/install-nix-action@v20
+        with:
+          extra_nix_config: |
+            trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ= loony-tools:pr9m4BkM/5/eSTZlkQyRt57Jz7OMBxNSUiMC4FkcNfk=
+            substituters = https://cache.nixos.org/ https://cache.iog.io/ https://cache.zw3rk.com
+          nix_path: nixpkgs=channel:nixos-unstable
+
+      - name: Display flake metadata
+        id: flake-metadata
+        run: |
+          echo $PWD
+          ls -lah .
+          nix flake metadata ${{ env.FLAKE_REF }}
+          nix flake metadata ${{ env.FLAKE_REF }} --json | jq -r '"LOCKED_URL=\(.url)"' >> "$GITHUB_OUTPUT"
+
+      - name: Wait for nix-tools meta job
+        uses: input-output-hk/actions/wait-for-hydra@angerman/support-prs
+        with:
+          status: 'ci/hydra-build:nix-tools'
+
+      - name: "Pull nix-tools"
+        run: |
+          ls -lah .
+          cp $(nix build --builders "" --max-jobs 0 ${{ steps.flake-metadata.outputs.LOCKED_URL }}#hydraJobs.aarch64-darwin.nix-tools-static-no-ifd --no-link --print-out-paths)/*.zip .
+          cp $(nix build --builders "" --max-jobs 0 ${{ steps.flake-metadata.outputs.LOCKED_URL }}#hydraJobs.x86_64-darwin.nix-tools-static-no-ifd --no-link --print-out-paths)/*.zip .
+          cp $(nix build --builders "" --max-jobs 0 ${{ steps.flake-metadata.outputs.LOCKED_URL }}#hydraJobs.x86_64-linux.nix-tools-static-no-ifd --no-link --print-out-paths)/*.zip .
+          cp $(nix build --builders "" --max-jobs 0 ${{ steps.flake-metadata.outputs.LOCKED_URL }}#hydraJobs.x86_64-linux.nix-tools-static-arm64-no-ifd --no-link --print-out-paths)/*.zip .
+
+      - name: Configure Git
+        if: startsWith(github.ref, 'refs/tags/')
+        run: |
+          git config --global user.name 'Auto Update Bot'
+          git config --global user.email '[email protected]'
+
+      - name: "Compute default.nix"
+        if: startsWith(github.ref, 'refs/tags/')
+        run: |
+          git fetch --all
+          git switch --force nix
+          (
+            echo "pkgs: let baseurl = \"https://github.com/input-output-hk/haskell-nix-example/releases/download/${GITHUB_REF_NAME}/\"; in {"
+            for arch in aarch64-darwin x86_64-darwin aarch64-linux x86_64-linux; do
+              echo "  ${arch} = pkgs.fetchurl { "
+              echo "     name = \"${arch}-nix-tools-static\";"
+              echo "     url = \"\${baseurl}${arch}-nix-tools-static.zip\";"
+              echo "     sha256 = \"$(nix-hash --sri --type sha256 --flat ${arch}-nix-tools-static.zip)\";"
+              echo "  };"
+            done
+            echo "}"
+          ) > default.nix
+          cat default.nix
+
+
+      - name: Push to nix branch
+        if: startsWith(github.ref, 'refs/tags/')
+        run: |
+          git add default.nix
+          git commit -m "update default.nix"
+          git push origin nix
+
+      - name: Release
+        uses: input-output-hk/action-gh-release@v1
+        if: startsWith(github.ref, 'refs/tags/')
+        with:
+          files: |
+            *-nix-tools-static.zip