refactor: use Buffer.from instead of deprecated constructor

lib/istanbul-local.js

@@ -46,7 +46,7 @@ exports.istanbulRequireHook = function(code, filename) {
 
     instrumentedCode = instrumentedCode.replace(inlineSourceMapRe, '')
       + '//# sourceMappingURL=data:application/json;base64,'
-      + new Buffer(sourceMapGenerator.toString()).toString('base64');
+      + Buffer.from(sourceMapGenerator.toString()).toString('base64');
 
     // Keep the consumer from the original source map, because the reports from Istanbul (not
     // Constantinople) are already mapped against the code.

scripts/changelog.ts

@@ -55,7 +55,7 @@ export default function(args: ChangelogOptions, logger: logging.Logger) {
         const commit = chunk.toString('utf-8')
           .replace(/https?:\/\/github.com\/(.*?)\/issues\/(\d+)/g, '@$1#$2');
 
-        callback(undefined, new Buffer(commit));
+        callback(undefined, Buffer.from(commit));
       }))
       .pipe(conventionalCommitsParser({
         headerPattern: /^(\w*)(?:\(([^)]*)\))?: (.*)$/,