Fix typo (#298)

src/locales/en/messages.json

@@ -775,7 +775,7 @@
     "message": "Warning"
   },
   "exportWarning": {
-    "message": "This export contains your unencrypted data in .csv format. You should not store or send it over unsecure channels (such as email). Delete it immediately after your are done using it."
+    "message": "This export contains your unencrypted data in .csv format. You should not store or send it over unsecure channels (such as email). Delete it immediately after you are done using it."
   },
   "exportMasterPassword": {
     "message": "Enter your master password to export your vault data."