add pact executor based on docker image

src/executors/default.yml

@@ -2,11 +2,11 @@ description: >
   This is a sample executor using Docker and Node. If you want to provide a custom environment in your orb, insert your image here.
   If you do not require an executor, you can simply delete this directory.
 docker:
-  - image: 'cimg/node:<<parameters.tag>>'
+  - image: "pactfoundation/pact-cli:<<parameters.tag>>"
 parameters:
   tag:
-    default: lts
+    default: latest
     description: >
-      Pick a specific cimg/node image variant:
-      https://hub.docker.com/r/cimg/node/tags
+      Pick a specific pact version to use:
+      https://hub.docker.com/r/pactfoundation/pact-cli/tags/
     type: string