Add aarch64 runner (#16)

* [CI] Add AArch64 GitHub Action Workflow

* Add a new GitHub Actions workflow for AArch64 builds using ArchLinux example from https://github.com/marketplace/actions/arm-runner. This prepares an ArchLinux image, sets up the nix environment, and builds the project for AArch64.

* [FIX] Fix Aarch64 workflow build system

* Fix the matrix.machine.platform with aarch64-linux in Nix build commands.

* [FIX] Fix build steps in aarch64 workflow

* Move the 'Build system' task to correctly follow the cache setup.

* [CI] Add permissions to CI workflows and update build steps

* Updated the CI workflows to include `contents: read` and `id-token: write` permissions. Also adjusted build commands to focus on `otb-dev` target and included the use of `magic-nix-cache-action`.

* [CI] Remove deprecated aarch64 GitHub Actions workflow

* The aarch64 GitHub Actions workflow file (.github/workflows/aarch64.yml) was deleted.

* This action is no more needed as the ci.yml works fine with Nix-Magic-Cache

* Rather than building 2 derivation i.e. otb-dev (all modules) and otb (minimal modules) which takes a lot of time for ARM64 build and gets timed out so we build only one derivation i.e otb-dev which contains all the modules.

.github/workflows/ci.yml

@@ -9,6 +9,9 @@ on:
 jobs:
   build:
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      id-token: write
     strategy:
       fail-fast: false
       matrix:
@@ -28,7 +31,7 @@ jobs:
             http-connections = 128
             max-substitution-jobs = 128
             extra-platforms = aarch64-linux
+      - uses: DeterminateSystems/magic-nix-cache-action@main
       - name: Build system
         run: |
           nix build --system ${{ matrix.machine.platform }} .#otb-dev
-          nix build --system ${{ matrix.machine.platform }} .#otb