Bump vue from 2.5.20 to 2.5.21 in /apps/accessibility

Bumps [vue](https://github.com/vuejs/vue) from 2.5.20 to 2.5.21.
- [Release notes](https://github.com/vuejs/vue/releases)
- [Commits](https://github.com/vuejs/vue/compare/v2.5.20...v2.5.21)

Signed-off-by: dependabot[bot] <support@dependabot.com>

apps/accessibility/package-lock.json

@@ -2538,7 +2538,8 @@
         "ansi-regex": {
           "version": "2.1.1",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "aproba": {
           "version": "1.2.0",
@@ -2953,7 +2954,8 @@
         "safe-buffer": {
           "version": "5.1.1",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "safer-buffer": {
           "version": "2.1.2",
@@ -3009,6 +3011,7 @@
           "version": "3.0.1",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "ansi-regex": "^2.0.0"
           }
@@ -3052,12 +3055,14 @@
         "wrappy": {
           "version": "1.0.2",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "yallist": {
           "version": "3.0.2",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         }
       }
     },
@@ -5608,9 +5613,9 @@
       }
     },
     "vue": {
-      "version": "2.5.20",
-      "resolved": "https://registry.npmjs.org/vue/-/vue-2.5.20.tgz",
-      "integrity": "sha512-kVLZi8RWOk8qwAt+a0bVDy9VV5Zzcnj0fLCMyKLx1dmEBjqmYJYRWHvPwiypiJBtJkdmROy5NP5hyDqTdfBcvQ=="
+      "version": "2.5.21",
+      "resolved": "https://registry.npmjs.org/vue/-/vue-2.5.21.tgz",
+      "integrity": "sha512-Aejvyyfhn0zjVeLvXd70h4hrE4zZDx1wfZqia6ekkobLmUZ+vNFQer53B4fu0EjWBSiqApxPejzkO1Znt3joxQ=="
     },
     "vue-hot-reload-api": {
       "version": "2.3.1",

apps/accessibility/package.json

@@ -12,7 +12,7 @@
 	},
 	"dependencies": {
 		"axios": "^0.18.0",
-		"vue": "^2.5.20"
+		"vue": "^2.5.21"
 	},
 	"browserslist": [
 		"last 2 versions",