Pin shared workflow and drop secrets inherit

Author: sshevchenko

.github/workflows/ci.yml

@@ -7,8 +7,7 @@ on:
 
 jobs:
   test:
-    uses: evolution-gaming/scala-github-actions/.github/workflows/ci.yml@v6
-    secrets: inherit
+    uses: evolution-gaming/scala-github-actions/.github/workflows/ci.yml@2a389d2a5f4b093e72f738464bd7472bd0c3b4b8 # v6
     with:
       scala_versions: '["2.13.16", "3.3.6"]'
       # TODO no sbt-version-policy in this repo, so binary compatibility was never checked