Use rust-cache action and prettify

Run `prettier` on the workflow file

.github/workflows/rust.yml

@@ -11,11 +11,14 @@ env:
 
 jobs:
   build:
-
     runs-on: ubuntu-latest
 
     steps:
       - uses: actions/checkout@v2
+
+      - name: Cache Packages
+        uses: Swatinem/rust-cache@v1.0.1
+
       - name: Build
         run: cargo build --release