chore(deps): bump vue-i18n from 8.15.0 to 8.15.1 in /frontend (#925)

Bumps [vue-i18n](https://github.com/kazupon/vue-i18n) from 8.15.0 to 8.15.1.
- [Release notes](https://github.com/kazupon/vue-i18n/releases)
- [Changelog](https://github.com/kazupon/vue-i18n/blob/dev/CHANGELOG.md)
- [Commits](https://github.com/kazupon/vue-i18n/compare/v8.15.0...v8.15.1)

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

frontend/package-lock.json

@@ -11836,9 +11836,9 @@
       "dev": true
     },
     "vue-i18n": {
-      "version": "8.15.0",
-      "resolved": "https://registry.npmjs.org/vue-i18n/-/vue-i18n-8.15.0.tgz",
-      "integrity": "sha512-juJ/avAP39bOMycC+qQDLJ8U9z9LtLF/9PsRoJLBSfsYZo9bqYntyyX5QPicwlb1emJKjgxhZ3YofHiQcXBu0Q=="
+      "version": "8.15.1",
+      "resolved": "https://registry.npmjs.org/vue-i18n/-/vue-i18n-8.15.1.tgz",
+      "integrity": "sha512-GBbz8qYCu0U2LNu4IcuFLZiuyninG4k26knvhL7GZG5Ncp4RR2VKDEH6g8gQ6I+UUBCvH2MBQVPSdxWe4DBkPw=="
     },
     "vue-loader": {
       "version": "15.7.1",

frontend/package.json

@@ -19,7 +19,7 @@
     "noty": "^3.2.0-beta",
     "qrcode.vue": "^1.7.0",
     "vue": "^2.6.10",
-    "vue-i18n": "^8.15.0",
+    "vue-i18n": "^8.15.1",
     "vue-router": "^3.1.3",
     "vuex": "^3.1.2",
     "vuex-router-sync": "^5.0.0"