Must provide smalltalk-version

Author: fniephaus

.github/workflows/ci.yml

@@ -14,4 +14,6 @@ jobs:
     steps:
     - uses: actions/checkout@v1
     - uses: hpi-swa/setup-smalltalkCI@v1
+      with:
+        smalltalk-version: 'Squeak64-trunk'
     - run: smalltalkci --help