Bump lodash from 4.17.19 to 4.17.21 in /src

Bumps [lodash](https://github.com/lodash/lodash) from 4.17.19 to 4.17.21.
- [Release notes](https://github.com/lodash/lodash/releases)
- [Commits](https://github.com/lodash/lodash/compare/4.17.19...4.17.21)

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

README.md

@@ -2,8 +2,7 @@
 Cucko is a Google Chrome browser extension that lets you hide the number of likes, retweets and replies a tweet has.
 
 ## Installation
-
+[Download the extension](https://chrome.google.com/webstore/detail/cuckoo-for-twitter/agjappnhmfoffegbhnakelgilanmnibb) from the Chrome web store here.
-You can no longer install this extension.
 
 ## Development
 To get set up for local development, follow these steps:

src/package-lock.json

@@ -2785,9 +2785,9 @@
       }
     },
     "lodash": {
-      "version": "4.17.19",
+      "version": "4.17.21",
-      "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.19.tgz",
+      "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.21.tgz",
-      "integrity": "sha512-JNvd8XER9GQX0v2qJgsaN/mzFCNA5BRe/j8JN9d+tWyGLSodKQHKFicdwNYzWwI3wjRnaKPsGj1XkBjx/F96DQ==",
+      "integrity": "sha512-v2kDEe57lecTulaDIuNTPy3Ry4gLGJ6Z1O3vE1krgXZNrsQ+LFTGHVxVjcXPs17LhbZVGedAJv8XZ1tvj5FvSg==",
       "dev": true
     },
     "lodash.memoize": {