update a few dependencies so that the build's succeed

The old dependencies no longer build on newer versions of node.
This commit changes nothing but those dependencies and a small
change to the gulp script to work with gulp 4+.

gulpfile.babel.js

@@ -31,4 +31,4 @@ gulp.task('clean', () => {
   .pipe(rimraf())
 })
 
-gulp.task('default', ['transpile', 'assets'])
+gulp.task('default', gulp.series('transpile', 'assets'));

package.json

@@ -15,19 +15,19 @@
     },
     "dependencies": {
         "args": "1.3.0",
-        "babel-core": "6.3.26",
+        "babel-core": "^6.26.3",
         "babel-eslint": "6.0.4",
         "babel-polyfill": "6.3.14",
         "babel-preset-es2015": "6.3.13",
         "babel-register": "6.9.0",
-        "body-parser": "1.10.2",
+        "body-parser": "^1.19.0",
         "cors": "2.7.1",
         "debug": "3.0.1",
         "email-regex": "1.0.0",
-        "express": "4.15.4",
+        "express": "^4.17.1",
+        "gulp": "4.0.2",
         "gulp-babel": "6.1.1",
         "gulp-rimraf": "0.2.0",
-        "gulp": "3.9.0",
         "hostenv": "1.0.1",
         "opentype.js": "0.4.4",
         "socket.io": "2.0.3",
@@ -38,7 +38,7 @@
     "devDependencies": {
         "eslint": "2.12.0",
         "eslint-config-default": "0.2.0",
-        "mocha": "2.2.4",
+        "mocha": "9.1.3",
         "nock": "2.17.0",
         "supertest": "0.15.0"
     },