chore: use stable rustfmt

Author: marcoieni

.github/actions/run-fixtures-test/action.yml

@@ -18,7 +18,7 @@ runs:
   using: composite
   steps:
     - name: Install toolchain
-      uses: dtolnay/rust-toolchain@nightly
+      uses: dtolnay/rust-toolchain@stable
 
     - name: Install git-cliff
       run: cargo install --path git-cliff/ --profile dev

.github/workflows/ci.yml

@@ -47,7 +47,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Install toolchain
-        uses: dtolnay/rust-toolchain@nightly
+        uses: dtolnay/rust-toolchain@stable
       - name: Checkout
         if: github.event_name != 'pull_request'
         uses: actions/checkout@v4
@@ -84,7 +84,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Install toolchain
-        uses: dtolnay/rust-toolchain@nightly
+        uses: dtolnay/rust-toolchain@stable
         with:
           components: clippy
       - name: Checkout
@@ -123,7 +123,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Install toolchain
-        uses: dtolnay/rust-toolchain@nightly
+        uses: dtolnay/rust-toolchain@stable
         with:
           components: rustfmt
       - name: Checkout

CONTRIBUTING.md

@@ -45,8 +45,6 @@ env UPDATE_EXPECT=1 cargo test
 
 7. Make sure [rustfmt](https://github.com/rust-lang/rustfmt) and [clippy](https://github.com/rust-lang/rust-clippy) don't complain about your changes.
 
-We use the `nightly` channel for `rustfmt` so please set the appropriate settings for your editor/IDE for that.
-
 ## Create a Pull Request
 
 1. Ensure that you updated the documentation and filled the [Pull Request template](./.github/PULL_REQUEST_TEMPLATE.md) according to the changes you made.