Compile for arm64 in GitHub Actions

Cross-architecture compile for arm64 on GitHub Actions' ubuntu-latest hosted runner.
See https://learn.microsoft.com/dotnet/core/deploying/native-aot/cross-compile#linux.
Effectively a revert of #973.

.github/dependabot.yml

@@ -1,13 +1,5 @@
 version: 2
 updates:
-- package-ecosystem: docker
-  directory: "/"
-  schedule:
-    interval: daily
-    time: "05:30"
-    timezone: Europe/London
-  reviewers:
-    - "martincostello"
 - package-ecosystem: "github-actions"
   directory: "/"
   schedule:

.github/workflows/build.yml

@@ -52,6 +52,21 @@ jobs:
 
     steps:
 
+    - name: Setup arm64 support for native AoT
+      if: runner.os == 'Linux'
+      shell: bash
+      run: |
+        dpkg --add-architecture arm64
+        bash -c 'cat > /etc/apt/sources.list.d/arm64.list <<EOF
+        deb [arch=arm64] http://ports.ubuntu.com/ubuntu-ports/ jammy main restricted
+        deb [arch=arm64] http://ports.ubuntu.com/ubuntu-ports/ jammy-updates main restricted
+        deb [arch=arm64] http://ports.ubuntu.com/ubuntu-ports/ jammy-backports main restricted universe multiverse
+        EOF'
+        sed -i -e 's/deb http/deb [arch=amd64] http/g' /etc/apt/sources.list
+        sed -i -e 's/deb mirror/deb [arch=amd64] mirror/g' /etc/apt/sources.list
+        apt update
+        apt install --yes clang llvm binutils-aarch64-linux-gnu gcc-aarch64-linux-gnu zlib1g-dev:arm64
+
     - name: Checkout code
       uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
 

build.ps1

@@ -91,7 +91,7 @@ function DotNetPublish {
 
     if ($IsLinux -And (-Not $UseManagedRuntime)) {
         $additionalArgs += "--runtime"
-        $additionalArgs += "linux-x64"
+        $additionalArgs += "linux-arm64"
         $additionalArgs += "--self-contained"
         $additionalArgs += "true"
         $additionalArgs += "/p:AssemblyName=bootstrap"