fix(circleci): pin firefox version to 64

Author: moriahmaney

.circleci/config.yml

@@ -130,7 +130,7 @@ jobs:
           no_output_timeout: 15m
           command: |
             set -em
-            PORT=4568 BROWSER=firefox npm run test:integration
+            PORT=4568 VERSION=64 BROWSER=firefox npm run test:integration
       - store_test_results:
           path: reports/junit/wdio
       - store_artifacts: