chore(developer): update multer dependency for server

Removes Keyman Developer Server's transitive dependency on dicer by
updating multer to `1.4.5-lts.1`, which updates its dependency on
busboy.

See
expressjs/multer#1097 (comment)
for reasoning behind use of  `-lts.1` rather than a full release
version.

At some point in the future, multer will publish a full release with
this fix, at which point we can move back to a full release version.

Author: mcdurdin

developer/src/server/package.json

@@ -14,7 +14,7 @@
     "@sentry/node": "^6.16.1",
     "chalk": "^4.1.2",
     "express": "^4.17.2",
-    "multer": "^1.4.4",
+    "multer": "^1.4.5-lts.1",
     "ngrok": "^4.2.2",
     "open": "^8.4.0",
     "ws": "^8.3.0"