Add CI workflow

.github/workflows/ci.yml

@@ -0,0 +1,33 @@
+name: CI
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  fmt:
+    name: Format
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Install just
+        run: cargo install just
+      - name: Check
+        run: just check-fmt
+
+  check:
+    name: Check crate
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v3
+    - name: Install just
+      run: cargo install just
+    - name: Check
+      run: just check-crate