[CI] Add matrix strategy to CI workflow for multi-arch builds

* The CI pipeline now supports builds for both x86-64 and aarch64-linux platforms by introducing a matrix strategy.

* Additionally, steps have been included to set up QEMU for ARM64 and improved configurations for Nix to better handle multi-arch builds.

* Ref based on https://lgug2z.com/articles/building-and-privately-caching-x86-and-aarch64-nixos-systems-on-github-actions

.github/workflows/ci.yml

@@ -9,11 +9,25 @@ on:
 jobs:
   build:
     runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        machine:
+          - host: amd64
+            platform: x86-64-linux
+          - host: arm64
+            platform: arm64-linux
     steps:
       - uses: actions/checkout@v4
-      - name: Install Nix
-        uses: DeterminateSystems/nix-installer-action@main
-      - uses: DeterminateSystems/magic-nix-cache-action@main
+      - if: matrix.machine.platform == 'aarch64-linux'
+        uses: docker/setup-qemu-action@v3
+      - uses: DeterminateSystems/nix-installer-action@main
         with:
-          diagnostic-endpoint: ""
-      - run: nix build .
+          extra-conf: |
+            fallback = true
+            http-connections = 128
+            max-substitution-jobs = 128
+            extra-platforms = aarch64-linux
+      - name: Build system
+        run: |
+          nix build --system ${{ matrix.machine.platform }} .