ci: update key cache to have more cache hits

With this change we should get more cache hit rates since previously all PRs had a different cache key

Author: alan-agius4

.circleci/config.yml

@@ -15,7 +15,7 @@
 #             (Using the tag in not necessary when pinning by ID, but include it anyway for documentation purposes.)
 # **NOTE 2**: If you change the version of the docker images, also change the `cache_key` suffix.
 var_1: &docker_image circleci/node:10.16-browsers@sha256:d2a96fe1cbef51257ee626b5f645e64dade3e886f00ba9cb7e8ea65b4efe8db1
-var_2: &cache_key v2-nguniversal-{{ .Branch }}-{{ checksum "yarn.lock" }}-node-10.16
+var_2: &cache_key v2-nguniversal-{{ checksum "yarn.lock" }}-{{ checksum "WORKSPACE" }}-node-10.16
 
 # Settings common to each job
 var_3: &job_defaults