Bump version to 0.21 (#23)

Author: danielsn

action.yml

@@ -33,7 +33,7 @@ runs:
     - name: Install Rust
       uses: actions-rs/[email protected]
       with:
-        # From https://github.com/model-checking/kani/blob/kani-0.20.0/rust-toolchain.toml
+        # From https://github.com/model-checking/kani/blob/kani-0.21.0/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-2022-12-11
@@ -42,7 +42,7 @@ runs:
     - name: Install Kani
       shell: bash
       run: |
-        export KANI_VERSION="0.20.0";
+        export KANI_VERSION="0.21.0";
         cargo install --version $KANI_VERSION --locked kani-verifier;
         cargo-kani setup;