build(deps): bump mongoose from 5.7.3 to 5.7.5 in /backend

Bumps [mongoose](https://github.com/Automattic/mongoose) from 5.7.3 to 5.7.5.
- [Release notes](https://github.com/Automattic/mongoose/releases)
- [Changelog](https://github.com/Automattic/mongoose/blob/master/History.md)
- [Commits](https://github.com/Automattic/mongoose/compare/5.7.3...5.7.5)

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

backend/package.json

@@ -3,7 +3,7 @@
     "async": "^3.1.0",
     "config": "^3.2.2",
     "express": "^4.17.1",
-    "mongoose": "^5.7.3",
+    "mongoose": "^5.7.5",
     "socket.io": "^2.3.0"
   },
   "scripts": {

backend/yarn.lock

@@ -426,10 +426,10 @@ mongoose-legacy-pluralize@1.0.2:
   resolved "https://registry.yarnpkg.com/mongoose-legacy-pluralize/-/mongoose-legacy-pluralize-1.0.2.tgz#3ba9f91fa507b5186d399fb40854bff18fb563e4"
   integrity sha512-Yo/7qQU4/EyIS8YDFSeenIvXxZN+ld7YdV9LqFVQJzTLye8unujAWPZ4NWKfFA+RNjh+wvTWKY9Z3E5XM6ZZiQ==
 
-mongoose@^5.7.3:
-  version "5.7.3"
-  resolved "https://registry.yarnpkg.com/mongoose/-/mongoose-5.7.3.tgz#8bd46b561eaed1a4d4a6cdd81d5b23c2e30da846"
-  integrity sha512-CKCCCAhFnJRtmdmver8Ud9/NZ9m7D2H/xLgmrcL6cb9D4nril/idL8lsWWpBsJI81AOCVsktiZJ4X4vfo2S0fw==
+mongoose@^5.7.5:
+  version "5.7.5"
+  resolved "https://registry.yarnpkg.com/mongoose/-/mongoose-5.7.5.tgz#b787b47216edf62036aa358c3ef0f1869c46cdc2"
+  integrity sha512-BZ4FxtnbTurc/wcm/hLltLdI4IDxo4nsE0D9q58YymTdZwreNzwO62CcjVtaHhmr8HmJtOInp2W/T12FZaMf8g==
   dependencies:
     bson "~1.1.1"
     kareem "2.3.1"