Add scala steward

.github/workflows/scala-steward.yml

@@ -0,0 +1,18 @@
+on:
+  schedule:
+    - cron: '0 0 * * 0'
+
+name: Launch Scala Steward
+
+jobs:
+  scala-steward:
+    runs-on: ubuntu-22.04
+    name: Launch Scala Steward
+    steps:
+      - name: Launch Scala Steward
+        uses: scala-steward-org/scala-steward-action@v2
+        with:
+          github-app-id: ${{ secrets.SCALA_STEWARD_APP_ID }}
+          github-app-installation-id: ${{ secrets.SCALA_STEWARD_INSTALLATION_ID }}
+          github-app-key: ${{ secrets.SCALA_STEWARD_PRIVATE_KEY }}
+          github-app-auth-only: true

.scala-steward.conf

@@ -0,0 +1,5 @@
+updates.pin = [
+  { groupId = "org.scala-lang", artifactId = "scala-library", version = "2.12." }
+  { groupId = "com.lightbend.paradox", artifactId = "sbt-paradox", version = "0.9." }
+  { groupId = "com.lightbend.paradox", artifactId = "sbt-paradox-theme", version = "0.9." }
+]