Specify CI builder image

This should help fix the issue that CI can easily be broken if the CI image is not compatible and helps make it possible to test the CI image.

.circleci/config.yml

@@ -3,7 +3,7 @@ version: 2.1
 parameters:
   ci_builder_image:
     type: string
-    default: us-docker.pkg.dev/oplabs-tools-artifacts/images/ci-builder:latest
+    default: us-docker.pkg.dev/oplabs-tools-artifacts/images/ci-builder:v0.27.0
 
 orbs:
   go: circleci/go@1.8.0