ci: fix node-version matrix parameter name (#142)

Author: simoneb

.github/workflows/ci.yml

@@ -6,7 +6,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node-version: [10.x, 12.x, 14.x]
+        node: [10.x, 12.x, 14.x]
     name: Node ${{ matrix.node }}
     steps:
       - uses: actions/checkout@v1