Separate CI into build and format tasks

.github/workflows/rust.yml → .github/workflows/build.yml

@@ -1,4 +1,4 @@
-name: Rust
+name: build
 
 on:
   push:
@@ -16,8 +16,6 @@ jobs:
 
     steps:
     - uses: actions/checkout@v2
-    - name: Formatting
-      run: cargo fmt -- --check
     - name: Build
       run: cargo build
     - name: Run tests

.github/workflows/format.yml

@@ -0,0 +1,20 @@
+name: format
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Formatting
+      run: cargo fmt -- --check