chore(ci): fix corepack (#473)

Fix CI due to corepack issue:

- nodejs/corepack#612

The solution is to set `COREPACK_DEFAULT_TO_LATEST=0` as suggested here
nodejs/corepack#625 (comment)

Author: styfle

.github/workflows/ci.yml

@@ -16,6 +16,8 @@ jobs:
   test:
     name: Test on node ${{ matrix.node }} and ${{ matrix.os }}
     timeout-minutes: 20
+    env:
+      COREPACK_DEFAULT_TO_LATEST: '0'
     strategy:
       fail-fast: false
       matrix: