Add support for Rust 1.43 (#13)

.github/workflows/rustfmt.yml

@@ -4,10 +4,15 @@ on: [push]
 
 jobs:
   build:
-
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v1
-    - name: Run rustfmt
-      run: make format-check
+      - uses: actions/checkout@v1
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          profile: minimal
+          components: clippy, rustfmt
+          override: true
+      - name: Run rustfmt
+        run: make format-check