Revert "deps: manually add 10.x support to npm"

This reverts commit 55557ba.

PR-URL: #19837
Reviewed-By: Gus Caplan <me@gus.host>

Author: addaleax

deps/npm/lib/utils/unsupported.js

@@ -5,8 +5,7 @@ var supportedNode = [
   {ver: '6', min: '6.0.0'},
   {ver: '7', min: '7.0.0'},
   {ver: '8', min: '8.0.0'},
-  {ver: '9', min: '9.0.0'},
-  {ver: '10', min: '10.0.0'}
+  {ver: '9', min: '9.0.0'}
 ]
 var knownBroken = '<4.7.0'