Repository: validatorjs/validator.js (js)
Issue: isMobilePhone not valid number phone in VietNam
Hi @chriso .
I tried validator with number phone on VietNam with locate code `vi-VN`. But Number Mobile Phone changed on VietNam. With start number phone `08` so `isMobilePhone` not working with number phone `"0868891902"`. You can help to check Regex of isMobilePhone.
Example: 
`validator.isMobilePhone("0868891902", "vi-VN")` --> false
`validator.isMobilePhone("01646545327", "vi-VN")` --> true
Thanks You 👍 
Pull request description: fix: isMobilePhone Regular Expression for Vietnamese phone number
According to [this](https://en.wikipedia.org/wiki/Telephone_numbers_in_Vietnam) Vietnam phone number guide, we should accept 11 length phone numbers as valid when the number starts with the `84` country code. In addition, I am adding the `55` area code.

Closes #813  

## Checklist

- [X] PR contains only changes related; no stray files, etc.
- [ ] README updated (where applicable)
- [X] Tests written (where applicable)


Patch:
diff --git a/build-browser.js b/build-browser.js
index 6101d65..c863bd3 100644
--- a/build-browser.js
+++ b/build-browser.js
@@ -1,34 +1,32 @@
 /* eslint import/no-extraneous-dependencies: 0 */
-import fs from 'fs';
-import { rollup } from 'rollup';
-import babel from 'rollup-plugin-babel';
-import babelPresetEnv from '@babel/preset-env';
-import pkg from './package.json';
+import fs from "fs";
+import { rollup } from "rollup";
+import babel from "rollup-plugin-babel";
+import babelPresetEnv from "@babel/preset-env";
+import pkg from "./package.json";
 
 rollup({
-  entry: 'src/index.js',
+  entry: "src/index.js",
   plugins: [
     babel({
       presets: [[babelPresetEnv, { modules: false }]],
       babelrc: false,
     }),
   ],
-}).then(bundle => (
-  bundle.write({
-    dest: 'validator.js',
-    format: 'umd',
-    moduleName: pkg.name,
-    banner: (
-      `/*!\n${
-        String(fs.readFileSync('./LICENSE'))
-          .trim()
-          .split('\n')
-          .map(l => ` * ${l}`)
-          .join('\n')
-      }\n */`
-    ),
-  })
-)).catch((e) => {
-  process.stderr.write(`${e.message}\n`);
-  process.exit(1);
-});
+})
+  .then((bundle) =>
+    bundle.write({
+      dest: "validator.js",
+      format: "umd",
+      moduleName: pkg.name,
+      banner: `/*!\n${String(fs.readFileSync("./LICENSE"))
+        .trim()
+        .split("\n")
+        .map((l) => ` * ${l}`)
+        .join("\n")}\n */`,
+    })
+  )
+  .catch((e) => {
+    process.stderr.write(`${e.message}\n`);
+    process.exit(1);
+  });
diff --git a/package.json b/package.json
index 72573e3..2392153 100644
--- a/package.json
+++ b/package.json
@@ -48,7 +48,7 @@
     "mocha": "^6.2.3",
     "nyc": "^14.1.0",
     "rimraf": "^3.0.0",
-    "rollup": "^0.43.0",
+    "rollup": "^0.47.0",
     "rollup-plugin-babel": "^4.0.1",
     "uglify-js": "^3.0.19"
   },
@@ -72,4 +72,4 @@
     "node": ">= 0.10"
   },
   "license": "MIT"
-}
+}
\ No newline at end of file
diff --git a/src/lib/isMobilePhone.js b/src/lib/isMobilePhone.js
index b2839d6..48e167d 100644
--- a/src/lib/isMobilePhone.js
+++ b/src/lib/isMobilePhone.js
@@ -113,7 +113,7 @@ const phones = {
   'tr-TR': /^(\+?90|0)?5\d{9}$/,
   'uk-UA': /^(\+?38|8)?0\d{9}$/,
   'uz-UZ': /^(\+?998)?(6[125-79]|7[1-69]|88|9\d)\d{7}$/,
-  'vi-VN': /^(\+?84|0)((3([2-9]))|(5([2689]))|(7([0|6-9]))|(8([1-9]))|(9([0-9])))([0-9]{7})$/,
+  'vi-VN': /^((\+?84)|0)((3([2-9]))|(5([25689]))|(7([0|6-9]))|(8([1-9]))|(9([0-9])))([0-9]{7})$/,
   'zh-CN': /^((\+|00)86)?1([3456789][0-9]|4[579]|6[2567]|7[01235678]|9[012356789])[0-9]{8}$/,
   'zh-TW': /^(\+?886\-?|0)?9\d{8}$/,
 };


Test patch:
diff --git a/test/validators.js b/test/validators.js
index ef24ea4..fbc6951 100644
--- a/test/validators.js
+++ b/test/validators.js
@@ -6748,6 +6748,8 @@ describe('Validators', () => {
           '0892405867',
           '+84888696413',
           '0878123456',
+          '84781234567',
+          '0553803765',
         ],
         invalid: [
           '12345',
@@ -6759,6 +6761,8 @@ describe('Validators', () => {
           '+841698765432',
           '841626543219',
           '0533803765',
+          '08712345678',
+          '+0321234567',
         ],
       },
       {