Fix YAML syntax

Author: marcphilipp

.github/workflows/reproducible-build.yml

@@ -24,7 +24,8 @@ jobs:
     - name: Restore Gradle cache and display toolchains
       uses: ./.github/actions/run-gradle
       with:
-        arguments: --quiet \
+        arguments: |
+          --quiet \
           --configuration-cache
     - name: Build and compare checksums
       shell: bash