feat: Add support for arm64 architecture

This commit introduces support for the arm64 architecture by:

1.  **Updating the Dockerfile:**
    *   The `exporter/Dockerfile` now uses the `TARGETARCH` build argument to dynamically determine the correct path for `libiperf.so.0`. This allows the same Dockerfile to be used for building both `amd64` and `arm64` images.

2.  **Modifying GitHub Workflows:**
    *   The CI workflow (`.github/workflows/ci.yaml`) and the Release workflow (`.github/workflows/release.yml`) have been updated to build and push multi-architecture Docker images (`linux/amd64` and `linux/arm64`).
    *   This involves adding the `docker/setup-qemu-action` for cross-compilation and specifying the target platforms in the `docker/build-push-action`.

3.  **Helm Chart:**
    *   No changes were required for the Helm chart as the image tag will now point to a multi-arch manifest, and the default iperf3 server image (`networkstatic/iperf3:latest`) is assumed to be multi-arch. Node selectors in the chart are not architecture-specific.

These changes enable the deployment of the iperf3-monitor on Kubernetes clusters with arm64 nodes.

.github/workflows/ci.yaml

@@ -31,6 +31,9 @@ jobs:
       - name: Check out code
         uses: actions/checkout@v3
 
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
+
       - name: Extract metadata (tags, labels) for Docker
         id: meta
         uses: docker/metadata-action@v4
@@ -44,6 +47,7 @@ jobs:
           push: false # Do not push on PRs
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
+          platforms: linux/amd64,linux/arm64
 
   test:
     name: Run Tests

.github/workflows/release.yml

@@ -36,6 +36,9 @@ jobs:
       - name: Check out code
         uses: actions/checkout@v3
 
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
+
       - name: Log in to GitHub Container Registry
         uses: docker/login-action@v2
         with:
@@ -56,6 +59,7 @@ jobs:
           push: true
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
+          platforms: linux/amd64,linux/arm64
 
   package-and-publish-chart:
     name: Package and Publish Helm Chart