ci: Fix nightly patch

Author: Lysxia

.github/workflows/nightly.yaml

@@ -44,7 +44,7 @@ jobs:
       - name: Patch Cargo config for nightly
         run: |
           mkdir .cargo
-          echo -e "[patch.crates-io]\ncreusot-std = { path = "../creusot/creusot-std" }" > .cargo/config.toml
+          echo -e '[patch.crates-io]\ncreusot-std = { path = "../creusot/creusot-std" }' > .cargo/config.toml
 
       - name: Run Creusot
         run: cargo creusot prove -- -Fsolutions