Bump date-fns from 2.0.0-beta.3 to 2.0.0-beta.4 in /backend

Bumps [date-fns](https://github.com/date-fns/date-fns) from 2.0.0-beta.3 to 2.0.0-beta.4.
- [Release notes](https://github.com/date-fns/date-fns/releases)
- [Changelog](https://github.com/date-fns/date-fns/blob/master/CHANGELOG.md)
- [Commits](https://github.com/date-fns/date-fns/compare/v2.0.0-beta.3...v2.0.0-beta.4)

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

backend/package.json

@@ -55,7 +55,7 @@
     "cheerio": "~1.0.0-rc.3",
     "cors": "~2.8.5",
     "cross-env": "~5.2.0",
-    "date-fns": "2.0.0-beta.3",
+    "date-fns": "2.0.0-beta.4",
     "debug": "~4.1.1",
     "dotenv": "~8.0.0",
     "express": "^4.17.1",

backend/yarn.lock

@@ -972,7 +972,7 @@
     url-regex "~4.1.1"
     video-extensions "~1.1.0"
 
-"@metascraper/helpers@^5.6.3", "@metascraper/helpers@^5.6.5":
+"@metascraper/helpers@^5.6.5":
   version "5.6.5"
   resolved "https://registry.yarnpkg.com/@metascraper/helpers/-/helpers-5.6.5.tgz#6f42bd1a8e3243e051e7bb067145125cd6b37e09"
   integrity sha512-j9qxXqZ9k/uNkABlsVjNN2Z5pVtukDmZMZ0ACsob+m5o8/yo87GvRf/UJfTPtog9vZ/QwkLav5Hhl+10NC7QLw==
@@ -2814,10 +2814,10 @@ data-urls@^1.0.0:
     whatwg-mimetype "^2.2.0"
     whatwg-url "^7.0.0"
 
-date-fns@2.0.0-beta.3:
-  version "2.0.0-beta.3"
-  resolved "https://registry.yarnpkg.com/date-fns/-/date-fns-2.0.0-beta.3.tgz#2e28f5af945930f774ddd778e184d68227101d55"
-  integrity sha512-z5O262BvHPhwUvA1weXH+AZodygnZUcORERw8hjwBUrRPGrAo2e/rjXfC8Ykf1OGJZGDuLnK/WXbEZBIc0exGQ==
+date-fns@2.0.0-beta.4:
+  version "2.0.0-beta.4"
+  resolved "https://registry.yarnpkg.com/date-fns/-/date-fns-2.0.0-beta.4.tgz#3e1bf33a15da69481f81972c4a50aad762a81f2c"
+  integrity sha512-xekjYm7ZDBuzePM/GBodhi3hW3P8dd2RbuIOLBjet2E6EGFR82wHTTXCSGuDEoapqlDvsx88ymRsq85lbM7dDw==
 
 debug@2.6.9, debug@^2.1.2, debug@^2.2.0, debug@^2.3.3, debug@^2.6.8, debug@^2.6.9:
   version "2.6.9"