Unbreak cargo hack for non-libraries (#4)

.github/workflows/check.yml

@@ -66,8 +66,9 @@ jobs:
         uses: dtolnay/rust-toolchain@stable
       - name: cargo install cargo-hack
         uses: taiki-e/install-action@cargo-hack
+      # intentionally no target specifier; see https://github.com/jonhoo/rust-ci-conf/pull/4
       - name: cargo hack
-        run: cargo hack --feature-powerset check --lib --tests
+        run: cargo hack --feature-powerset check
   msrv:
     runs-on: ubuntu-latest
     # we use a matrix here just because env can't be used in job names