Install updated toolchain to the one from the kani release (#8)

Author: danielsn

action.yml

@@ -26,6 +26,15 @@ inputs:
 runs:
   using: "composite"
   steps:
+    - name: Install Rust
+      uses: actions-rs/[email protected]
+      with:
+        # From https://github.com/model-checking/kani/blob/kani-0.13.0/rust-toolchain.toml
+        # Should be updated every time we update the version to keep in sync.
+        # This should be automated https://github.com/model-checking/kani-github-action/issues/9
+        toolchain: nightly-2022-10-11
+        override: true
+
     - name: Install Kani
       shell: bash
       run: |