test: blindly attempt to re-enable nightly

I disabled this in nodejs#404. This is a PR so I can futz around with it and
try to figure out why the mirror isn't working.

.github/workflows/push.yml

@@ -19,11 +19,10 @@ jobs:
           - version: 14.x
           - version: 16.x
           - version: 18.x
-          # These error with "Unexpected input(s) 'node-mirror' ...":
-          # - version: 19.x
-          #   mirror: https://nodejs.org/download/nightly
-          # - version: 19.x
-          #   mirror: https://nodejs.org/download/v8-canary
+          - version: 19.x
+            mirror: https://nodejs.org/download/nightly
+          - version: 19.x
+            mirror: https://nodejs.org/download/v8-canary
         # os: [ubuntu-latest, macos-latest]
         # Temporarily disable MacOS until
         # https://github.com/nodejs/node/issues/32981 is fixed
@@ -36,7 +35,7 @@ jobs:
     steps:
       - uses: actions/checkout@v3
       - name: Use Node.js ${{ matrix.node.version }} ${{ matrix.node.mirror }}
-        uses:  No9/setup-node@mirror
+        uses: No9/setup-node@mirror
         with:
           node-version: ${{ matrix.node.version }}
           # TODO(mmarchini): re-enable once mirror is supported on setup-node