CI: Simplify backend-lint job

CI is already using the `minimal` profile by default and the `rustup update` call seems to be unnecessary

Author: Turbo87

.github/workflows/ci.yml

@@ -74,12 +74,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2
 
-      - name: Install Rust
-        run: |
-          rustup set profile minimal
-          rustup update 1.56.0
-          rustup default 1.56.0
-
+      - run: rustup default 1.56.0
       - run: rustup component add rustfmt
       - run: rustup component add clippy