use nightly fmt in workflow

Author: talhadaar

.github/workflows/pr-check.yml

@@ -22,7 +22,10 @@ jobs:
         uses: actions/checkout@v3
         with:
           fetch-depth: 1
-      
+
+      - name: Install nightly toolchain
+        run: rustup toolchain install nightly --component rustfmt
+
       - name: "[Check] cargo fmt"
         run: cargo fmt --check