Add node.js 13 to testing

Normalize output changes to match node.js 12.

.travis.yml

@@ -1,6 +1,7 @@
 language: node_js
 
 node_js:
+  - 13
   - 12
   - 10
   - 8

test/spawn.js

@@ -116,7 +116,8 @@ const main = () => {
       stdio: [0, 1, 2]
     })
     t.plan(1)
-    s.main(() => t.matchSnapshot(s.output))
+    // Fixup for errno property change in 13.x
+    s.main(() => t.matchSnapshot(s.output.replace(/errno: -2/, 'errno: ENOENT')))
   })
 
   t.test('failure to spawn even harder', t => {

test/tap/index.js

@@ -35,7 +35,13 @@ module.exports = (...test) => {
         signal: signal
       }, 'exit status')
       t.matchSnapshot(out, 'stdout')
-      t.matchSnapshot(err, 'stderr')
+      t.matchSnapshot(
+        err.split('\n')
+          // Remove node.js 13.0.0+ message:
+          .filter(a => a !== '(Use `node --trace-uncaught ...` to show where the exception was thrown)')
+          .join('\n'),
+        'stderr'
+      )
     })
   }
 }