Bump mongoose from 5.13.13 to 5.13.15

Bumps [mongoose](https://github.com/Automattic/mongoose) from 5.13.13 to 5.13.15.
- [Release notes](https://github.com/Automattic/mongoose/releases)
- [Changelog](https://github.com/Automattic/mongoose/blob/master/CHANGELOG.md)
- [Commits](https://github.com/Automattic/mongoose/compare/5.13.13...5.13.15)

---
updated-dependencies:
- dependency-name: mongoose
  dependency-type: direct:production
...

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

package.json

@@ -58,7 +58,7 @@
     "got": "^11.8.5",
     "helmet": "^4.5.0",
     "mongodb": "^3.6.6",
-    "mongoose": "^5.12.5",
+    "mongoose": "^5.13.15",
     "redis": "^3.1.2",
     "rss-parser": "^3.12.0",
     "tough-cookie": "^4.0.0",

yarn.lock

@@ -1533,9 +1533,9 @@ mongoose-legacy-pluralize@1.0.2:
   version "1.0.2"
   resolved "https://registry.npmjs.org/mongoose-legacy-pluralize/-/mongoose-legacy-pluralize-1.0.2.tgz"
 
-mongoose@^5.12.5:
-  version "5.13.13"
-  resolved "https://registry.npmjs.org/mongoose/-/mongoose-5.13.13.tgz"
+mongoose@^5.13.15:
+  version "5.13.15"
+  resolved "https://registry.yarnpkg.com/mongoose/-/mongoose-5.13.15.tgz#ba2cd0f22c1a5dd9ae15aaf6b10f03c59a4202dd"
   dependencies:
     "@types/bson" "1.x || 4.0.x"
     "@types/mongodb" "^3.5.27"