Update tooling to latest versions

gulpfile.js

@@ -16,8 +16,6 @@ var sources = [
     'theme.toml'
 ];
 
-gulp.task('default', ['build']);
-gulp.task('build', ['sass']);
 
 gulp.task('release', function () {
     return gulp.src(sources)
@@ -42,3 +40,6 @@ gulp.task('clean', function () {
 gulp.task('watch', function () {
     return gulp.watch('./src/*.scss', ['sass']);
 });
+
+gulp.task('build', gulp.series('sass'));
+gulp.task('default', gulp.series('build'));

package.json

@@ -3,13 +3,13 @@
     "bulma": "^0.7.2"
   },
   "devDependencies": {
-    "@fortawesome/fontawesome-free": "^5.7.1",
+    "@fortawesome/fontawesome-free": "^5.7.2",
-    "gulp": "^3.9.1",
+    "gulp": "^4.0.0",
-    "gulp-clean": "^0.3.2",
+    "gulp-clean": "^0.4.0",
-    "gulp-gzip": "^1.4.0",
+    "gulp-gzip": "^1.4.2",
-    "gulp-sass": "^3.1.0",
+    "gulp-sass": "^4.0.2",
-    "gulp-sourcemaps": "^1.9.1",
+    "gulp-sourcemaps": "^2.6.5",
-    "gulp-tar-path": "^1.0.1",
+    "gulp-tar-path": "^1.0.2",
-    "octicons": "^0.0.0-882a0ed25"
+    "octicons": "^8.5.0"
   }
 }