build: support Node.js 13.x

Author: dougwilson

.travis.yml

@@ -14,13 +14,7 @@ node_js:
   - "10.20"
   - "11.15"
   - "12.16"
-matrix:
-  include:
-    - node_js: "13"
-      env: "NVM_NODEJS_ORG_MIRROR=https://nodejs.org/download/nightly"
-  allow_failures:
-    # Allow the nightly installs to fail
-    - env: "NVM_NODEJS_ORG_MIRROR=https://nodejs.org/download/nightly"
+  - "13.14"
 cache:
   directories:
     - node_modules

appveyor.yml

@@ -14,6 +14,7 @@ environment:
     - nodejs_version: "10.20"
     - nodejs_version: "11.15"
     - nodejs_version: "12.16"
+    - nodejs_version: "13.14"
 cache:
   - node_modules
 install: