Update ruby/setup-ruby action to v1.320.0

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/pr-build.yml

@@ -36,7 +36,7 @@ jobs:
           node-version: 24.18.0
 
       - name: Set up Ruby
-        uses: ruby/setup-ruby@003a5c4d8d6321bd302e38f6f0ec593f77f06600 # v1.319.0
+        uses: ruby/setup-ruby@a30dfa457ad68707b8b910ac3a244714b61c0626 # v1.320.0
         with:
           bundler-cache: true
 

.github/workflows/site-build.yml

@@ -47,7 +47,7 @@ jobs:
           node-version: 24.18.0
 
       - name: Set up Ruby
-        uses: ruby/setup-ruby@003a5c4d8d6321bd302e38f6f0ec593f77f06600 # v1.319.0
+        uses: ruby/setup-ruby@a30dfa457ad68707b8b910ac3a244714b61c0626 # v1.320.0
         with:
           bundler-cache: true