Add sbt installation step to CI (#127)

Github removed sbt from the ubuntu runner image therefore we need to add sbt installation step to CI.

Author: spenes

.github/workflows/ci.yml

@@ -19,6 +19,9 @@ jobs:
       with:
         java-version: 11
 
+    - name: Install sbt
+      uses: sbt/setup-sbt@v1
+
     - name: Run tests
       run: sbt coverage +test
 

.github/workflows/release.yml

@@ -12,6 +12,9 @@ jobs:
     - uses: actions/checkout@v2
     - uses: coursier/cache-action@v6
 
+    - name: Install sbt
+      uses: sbt/setup-sbt@v1
+
     - name: Make site
       run: sbt makeSite