feat!: engines.node defaults to 16.0.0

node.js < 13, v15 has been eol.
and node.js v14 will be eol in a few months.

refs: #42

lib/util/get-configured-node-version.js

@@ -36,7 +36,7 @@ function getEnginesNode(filename) {
  *
  * 1. Parse a given version then return it if it's valid.
  * 2. Look package.json up and parse `engines.node` then return it if it's valid.
- * 3. Return `>=8.0.0`.
+ * 3. Return `>=16.0.0`.
  *
  * @param {string|undefined} version The version range text.
  * @param {string} filename The path to the current linting file.
@@ -52,7 +52,7 @@ module.exports = function getConfiguredNodeVersion(context) {
     return (
         getSemverRange(version) ||
         getEnginesNode(filePath) ||
-        getSemverRange(">=8.0.0")
+        getSemverRange(">=16.0.0")
     )
 }