circleci: use xlarge instance for bedrock-checks

I measured the required mem usage and it is 8545MB on CircleCI at the
moment. I'm not sure why upstream needs so much less.

The high memory usage might be caused by foundry-rs/foundry#6411

.circleci/config.yml

@@ -188,7 +188,7 @@ jobs:
   contracts-bedrock-checks:
     docker:
       - image: <<pipeline.parameters.ci_builder_image>>
-    resource_class: large
+    resource_class: xlarge
     steps:
       - checkout
       - run: