🐛 Fixed csv file uploads on Windows w/Excel installed

no issue

- refs https://forum.ghost.org/t/import-json-file-from-v-2-34-0-to-v-3-0-3-ignores-my-subscribers/10324
- Windows machines that have excel installed use a weird mime type for CSV files
- Users can fix this by adjusting their registry, but that's annoying
- We should just allow this, it doesn't really change anything & we still require .csv as the extension

core/server/config/overrides.json

@@ -25,7 +25,7 @@
     "uploads": {
         "members": {
             "extensions": [".csv"],
-            "contentTypes": ["text/csv", "application/csv", "application/octet-stream"]
+            "contentTypes": ["text/csv", "application/csv", "application/octet-stream", "application/vnd.ms-excel"]
         },
         "images": {
             "extensions": [".jpg", ".jpeg", ".gif", ".png", ".svg", ".svgz", ".ico"],