Pin mitlibraries/.github action to 5ac3905

Author: renovate[bot]

.github/workflows/mit-libraries-ruby-ci.yml

@@ -7,4 +7,4 @@ on:
 
 jobs:
   shared:
-    uses: mitlibraries/.github/.github/workflows/ruby-shared-ci.yml@main
+    uses: mitlibraries/.github/.github/workflows/ruby-shared-ci.yml@5ac390549cb5d779971514d3b2da8ba1515ea5fc # main