ci: Test that cargo creusot new creates a compilable project

.github/workflows/rust.yml

@@ -106,3 +106,14 @@ jobs:
         cat ~/.config/creusot/why3.conf
     - run: cargo test --test why3 "" -- --replay=none --diff-from=origin/master
     - run: cargo test --test why3 "" -- --skip-unstable
+    - name: test cargo creusot new
+      # TODO: Figure out how to install creusot without rebuilding it
+      # For now, we use the executables in target/
+      run: |
+        echo /home/runner/work/creusot/creusot/target/debug >> $GITHUB_PATH
+        cd ..
+        cargo creusot new test-project --main --creusot-contracts ../creusot/creusot-contracts
+        cd test-project
+        cargo build
+        cargo creusot
+        cargo creusot prove