Fix CircleCI install (#864)

Author: josephjclark

.circleci/config.yml

@@ -14,7 +14,7 @@ jobs:
     steps:
       - run:
           name: Install pnpm
-          command: sudo corepack enable
+          command: sudo npm install -g corepack@latest && sudo corepack enable
       - checkout
       - restore_cache:
           # See the configuration reference documentation for more details on using restore_cache and save_cache steps

README.md

@@ -39,7 +39,7 @@ We use [`pnpm`](https://pnpm.io/installation), a fast, disk space efficient pack
 
 ## Installing
 
-This repo uses node corepack to ensure pnpm v8 is used.
+This repo uses node corepack to ensure pnpm v8 is used
 
 - `$ corepack enable`
 - `$ pnpm install`