Update the CI to take the rust-toolchain file into account

.github/workflows/flaky-tests.yml

@@ -17,9 +17,6 @@ jobs:
         apt-get update && apt-get install -y curl
         apt-get install build-essential -y
     - uses: actions-rs/toolchain@v1
-      with:
-        toolchain: stable
-        override: true
     - name: Install cargo-flaky
       run: cargo install cargo-flaky
     - name: Run cargo flaky in the dumps