CI: Check if we should run in bedrock-echidna-run (#4362)

The previous steps (required for this one) had the check changed script.
This means that the required build artifacts were not being created and
then cause this step to fail.

.circleci/config.yml

@@ -302,6 +302,14 @@ jobs:
     steps:
       - checkout
       - attach_workspace: {at: "."}
+      - run:
+          name: Check if we should run
+          command: |
+            shopt -s inherit_errexit
+            CHANGED=$(check-changed "(contracts-bedrock/contracts)" || echo "TRUE")
+            if [[ "$CHANGED" = "FALSE" ]]; then
+              circleci step halt
+            fi
       - run:
           name: Echidna Fuzz <<parameters.echidna_target>>
           command: yarn echidna:<<parameters.echidna_target>>