Bump underscore from 1.9.2 to 1.13.1

Bumps [underscore](https://github.com/jashkenas/underscore) from 1.9.2 to 1.13.1.
- [Release notes](https://github.com/jashkenas/underscore/releases)
- [Commits](https://github.com/jashkenas/underscore/compare/1.9.2...1.13.1)

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

services/spelling/package-lock.json

@@ -6325,9 +6325,9 @@
       "dev": true
     },
     "underscore": {
-      "version": "1.9.2",
-      "resolved": "https://registry.npmjs.org/underscore/-/underscore-1.9.2.tgz",
-      "integrity": "sha512-D39qtimx0c1fI3ya1Lnhk3E9nONswSKhnffBI0gME9C99fYOkNi04xs8K6pePLhvl1frbDemkaBQ5ikWllR2HQ=="
+      "version": "1.13.1",
+      "resolved": "https://registry.npmjs.org/underscore/-/underscore-1.13.1.tgz",
+      "integrity": "sha512-hzSoAVtJF+3ZtiFX0VgfFPHEDRm7Y/QPjGyNo4TVdnDTdft3tr8hEkD25a1jC+TjTuE7tkHGKkhwCgs9dgBB2g=="
     },
     "unpipe": {
       "version": "1.0.0",

services/spelling/package.json

@@ -35,7 +35,7 @@
     "mongodb": "^3.6.0",
     "request": "^2.88.2",
     "settings-sharelatex": "^1.1.0",
-    "underscore": "1.9.2"
+    "underscore": "1.13.1"
   },
   "devDependencies": {
     "bunyan": "^1.8.12",