fix sbt workflow

Author: ducky64

.github/workflows/pr-scala.yml

@@ -36,6 +36,8 @@ jobs:
     - uses: actions/setup-python@v1
       with:
         python-version: '3.10'
+    - name: Setup sbt launcher
+      uses: sbt/setup-sbt@v1
     - name: install dependencies
       run: pip install -r requirements.txt
     - name: sbt test