breaking: bump node support >=10.0.0 (#376)

diff --git a/.travis.yml b/.travis.yml
index dd562ab..a8cff29 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,8 +5,6 @@
   depth: 10
 
 node_js:
-  - 6
-  - 8
   - 10
   - 12
 
diff --git a/appveyor.yml b/appveyor.yml
index b241f46..c752a16 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -21,18 +21,18 @@
 
 environment:
   matrix:
-    - nodejs_version: "6"
+    - nodejs_version: "10"
       APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
 
-    - nodejs_version: "6"
+    - nodejs_version: "10"
       APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
       MSBUILDDIR: "C:\\Program Files (x86)\\Microsoft Visual Studio\\2017\\Community\\MSBuild\\15.0\\Bin\\"
 
-    - nodejs_version: "6"
+    - nodejs_version: "10"
       APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
       MSBUILDDIR: "C:\\Program Files (x86)\\MSBuild\\14.0\\bin\\"
 
-    - nodejs_version: "6"
+    - nodejs_version: "10"
       APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
 
 install:
diff --git a/package.json b/package.json
index d986787..e56039d 100644
--- a/package.json
+++ b/package.json
@@ -47,7 +47,7 @@
     "rewire": "^4.0.1"
   },
   "engines": {
-    "node": ">=6.0.0"
+    "node": ">=10.0.0"
   },
   "author": "Apache Software Foundation",
   "license": "Apache-2.0",