ci: ignore Node.js 8

> internal/streams/legacy.js:59
>      throw er; // Unhandled stream error in pipe.
>      ^
>
> Error: certificate has expired
>    at TLSSocket.<anonymous> (_tls_wrap.js:1116:38)
>    at emitNone (events.js:106:13)
>    at TLSSocket.emit (events.js:208:7)
>    at TLSSocket._finishInit (_tls_wrap.js:643:8)
>    at TLSWrap.ssl.onhandshakedone (_tls_wrap.js:473:38)

.github/workflows/ci.yml

@@ -10,7 +10,7 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [8.x, 10.x]
+        node-version: [10.x]
 
     steps:
       - uses: actions/checkout@v2