fix: disable using cache from node_module in circle ci

We have error on CI like this: "ganache-core-sc/node_modules/web3-providers-ws/node_modules/websocket: Appears to be a git repo or submodule."
After some attempt of removing more ".git" file under node_modules still fails. Disable the use of cache first.

- Failed CI: https://circleci.com/gh/omisego/plasma-contracts/2973
- related issue: OpenZeppelin/openzeppelin-sdk#929

.circleci/config.yml

@@ -19,9 +19,11 @@ commands:
       - run:
           name: Set up environment
           command: echo 'export PATH="$(npm bin):$PATH"' >> $BASH_ENV
-      - restore_cache:
-          keys:
-            - v2-dependencies-{{ checksum "plasma_framework/package-lock.json" }}
+      # FIXME: disable cache for error like: https://circleci.com/gh/omisego/plasma-contracts/2973
+      # the current workaround of "rm -rf node_modules/*/.git" fails to sovle this too.
+      # - restore_cache:
+      #     keys:
+      #       - v2-dependencies-{{ checksum "plasma_framework/package-lock.json" }}
       - run:
           name: Install dependencies
           working_directory: ~/repo/plasma_framework