added CI tests for macOS (#13)

Added a matrix to run the CI jobs, using both `ubuntu-latest` and
`macos-latest`.

Author: Bullrich

.github/workflows/ci.yml

@@ -13,20 +13,33 @@ concurrency:
 
 jobs:
   ci:
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
-      - name: Rust compilation prerequisites
+      - name: Rust compilation prerequisites (Ubuntu)
+        if: contains(matrix.os, 'ubuntu')
         run: |
           sudo apt update
           sudo apt install -y \
             protobuf-compiler
           rustup target add wasm32-unknown-unknown
           rustup component add rustfmt clippy rust-src
 
+      - name: Install Cargo (MacOS)
+        if: contains(matrix.os, 'macos')
+        run: |
+          curl https://sh.rustup.rs -sSf -y | sh
+          brew install protobuf
+          rustup target add wasm32-unknown-unknown --toolchain stable-aarch64-apple-darwin
+          rustup component add rust-src --toolchain stable-aarch64-apple-darwin
+
       # We've run into out-of-disk error when compiling Polkadot in the next step, so we free up some space this way.
       - name: Free Disk Space (Ubuntu)
+        if: contains(matrix.os, 'ubuntu')
         uses: jlumbroso/free-disk-space@54081f138730dfa15788a46383842cd2f914a1be # 1.3.1
         with:
           android: true # This alone is a 12 GB save.
@@ -58,7 +71,7 @@ jobs:
   build-docker:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       # We've run into out-of-disk error when compiling Polkadot in the next step, so we free up some space this way.
       - name: Free Disk Space (Ubuntu)