build(dependencies): Deps bump, primarily gulp from 3 to 4

gulpfile.js

@@ -1,6 +1,5 @@
 
-const gulp        = require( 'gulp' );
-const runSequence = require( 'run-sequence' );
+const gulp = require( 'gulp' );
 
 const child   = require( 'child_process' );
 const path    = require( 'path' );
@@ -30,57 +29,45 @@ gulp.task( 'make-build-dir', ( ) =>
 	mkdirp( buildRoot )
 );
 
-gulp.task( 'clone-libphonenumber', [ 'make-build-dir' ], ( ) =>
+gulp.task( 'clone-libphonenumber', gulp.series( 'make-build-dir', ( ) =>
 	gitClone( libphonenumberUrl, 'libphonenumber', libphonenumberVersion )
-);
+) );
 
-gulp.task( 'clone-closure-library', [ 'make-build-dir' ], ( ) =>
+gulp.task( 'clone-closure-library', gulp.series( 'make-build-dir', ( ) =>
 	gitClone( closureLibraryUrl, 'closure-library', 'v20171112' )
-);
+) );
 
-gulp.task( 'checkout-closure-linter', [ 'make-build-dir' ], ( ) =>
+gulp.task( 'checkout-closure-linter', gulp.series( 'make-build-dir', ( ) =>
 	gitClone( closureLinterUrl, 'closure-linter' )
-);
+) );
 
-gulp.task( 'checkout-python-gflags', [ 'make-build-dir' ], ( ) =>
+gulp.task( 'checkout-python-gflags', gulp.series( 'make-build-dir', ( ) =>
 	gitClone( pythonGflagsUrl, 'python-gflags' )
-);
+) );
 
-gulp.task( 'download-deps', [
+gulp.task( 'download-deps', gulp.parallel(
 	'clone-libphonenumber',
 	'clone-closure-library',
 	'checkout-closure-linter',
 	'checkout-python-gflags'
-] );
+) );
 
-gulp.task( 'build-deps', [ 'download-deps' ] );
+gulp.task( 'build-deps', gulp.series( 'download-deps' ) );
 
 gulp.task( 'build-libphonenumber', ( ) => {
 	var args = [ '-f', 'build.xml', 'compile-exports' ];
 	return runCommand( 'ant', args, { cwd: '.' } );
 } );
 
-gulp.task( 'build', cb =>
-	runSequence(
-		'build-deps',
-		'build-libphonenumber',
-		cb
-	)
-);
+gulp.task( 'build', gulp.series( 'build-deps', 'build-libphonenumber' ) );
 
 gulp.task( 'update-readme', ( ) =>
 	updateReadme( )
 );
 
-gulp.task( 'default', [ 'clean' ], cb =>
-	runSequence(
-		'build',
-		'update-readme',
-		cb
-	)
-);
+gulp.task( 'default', gulp.series( 'clean', 'build', 'update-readme' ) );
 
-function updateReadme( )
+async function updateReadme( )
 {
 	replace( {
 		regex: 'Uses libphonenumber ([A-Za-z.0-9]+)',

package.json

@@ -37,17 +37,16 @@
   "devDependencies": {
     "@types/mocha": "5.x",
     "chai": "4.x",
-    "cz-conventional-changelog": "^2.1.0",
+    "cz-conventional-changelog": "2.x",
     "google-closure-compiler": "20171023.0.1",
-    "gulp": "3.x",
+    "gulp": "4.x",
     "mkdirp": "0.x",
     "mocha": "5.x",
     "pre-commit": "1.x",
     "replace": "1.x",
     "rimraf-promise": "2.x",
-    "run-sequence": "2.x",
-    "semantic-release": "^15.12.4",
-    "typescript": "2.8.x"
+    "semantic-release": "15.x",
+    "typescript": "3.x"
   },
   "config": {
     "commitizen": {