Pin node-gyp back to fix GitHub Actions (#192)

This should fix the current failing GitHub Workflow CI job.

Maybe Related: osrf/docker_images#334
See Also: osrf/docker_images#333

Using 7.0.0 or newer causes failures.
Bumping all dependencies also seemed to work but brings other issues.
This PR is the minimum change required.

.github/workflows/ci.yaml

@@ -1,6 +1,6 @@
 name: Node.js CI
 
-on: [push]
+on: [push, pull_request]
 
 jobs:
   build:
@@ -29,7 +29,7 @@ jobs:
     # - run: sudo chmod 755 /usr/bin/google-chrome
     # - run: defaults write com.google.chrome HardwareAccelerationModeEnabled -integer 1
     # - run: export DISPLAY=:0
-    - run: npm run deploy
+    - run: npm run deploy --verbose
     # - run: npm test
     # - run: npm run coverage
     - run: npm run update

package.json

@@ -22,7 +22,7 @@
   "dependencies": {
     "fs": "0.0.1-security",
     "http": "0.0.0",
-    "node-gyp": "",
+    "node-gyp": "6.1.0",
     "path": "^0.12.7",
     "websocket": "^1.0.25"
   },