ci: fix syntax

Author: haoqunjiang

.github/workflows/nodejs.yml

@@ -24,6 +24,6 @@ jobs:
         with:
           node-version: ${{ matrix.node-version }}
       - run: yarn add -D jest@25 ts-jest@25 @types/jest@25 prettier@1
-        if: ${{ node-version == '8.x' }}
+        if: ${{ matrix.node-version == '8.x' }}
       - run: yarn --pure-lockfile
       - run: yarn test