Temporarily revert Node to v16 to avoid some teething problems with v18

A few rough edges, notably around old TLS support, IPv6/IPv4 defaults,
and a JSStreamSocket finishShutdown unhandled error.

v16 EOL isn't until September so worth rolling back for a couple of
months while we tidy that up a little more.

Author: pimterry

.github/workflows/ci.yml

@@ -16,7 +16,7 @@ jobs:
 
       - uses: actions/setup-node@v3
         with:
-          node-version: 18.16.0
+          node-version: 16.20.1
 
       - run: npm install -g npm@^8
 

package.json

@@ -184,7 +184,7 @@
         }
       },
       "node": {
-        "version": "18.16.0",
+        "version": "16.20.1",
         "targets": [
           "win32-x64",
           "linux-x64",