Bump lodash from 4.17.15 to 4.17.21 in /twistter-frontend

Bumps [lodash](https://github.com/lodash/lodash) from 4.17.15 to 4.17.21.
- [Release notes](https://github.com/lodash/lodash/releases)
- [Commits](https://github.com/lodash/lodash/compare/4.17.15...4.17.21)

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

functions/package-lock.json

@@ -673,14 +673,6 @@
         "readable-stream": "~1.0.32"
       }
     },
-    "busboy": {
-      "version": "0.3.1",
-      "resolved": "https://registry.npmjs.org/busboy/-/busboy-0.3.1.tgz",
-      "integrity": "sha512-y7tTxhGKXcyBxRKAni+awqx8uqaJKrSFSNFSeRG5CsWNdmy2BIK+6VGWEW7TZnIO/533mtMEA4rOevQV815YJw==",
-      "requires": {
-        "dicer": "0.3.0"
-      }
-    },
     "bytebuffer": {
       "version": "5.0.1",
       "resolved": "https://registry.npmjs.org/bytebuffer/-/bytebuffer-5.0.1.tgz",
@@ -3715,9 +3707,9 @@
       "integrity": "sha512-LKYU1iAXJXUgAXn9URjiu+MWhyUXHsvfp7mcuYm9dSUKK0/CjtrUwFAxD82/mCWbtLsGjFIad0wIsod4zrTAEQ=="
     },
     "y18n": {
-      "version": "3.2.2",
+      "version": "3.2.1",
-      "resolved": "https://registry.npmjs.org/y18n/-/y18n-3.2.2.tgz",
+      "resolved": "https://registry.npmjs.org/y18n/-/y18n-3.2.1.tgz",
-      "integrity": "sha512-uGZHXkHnhF0XeeAPgnKfPv1bgKAYyVvmNL1xlKsPYZPaIHxGti2hHqvOCQv71XMsLxu1QjergkqogUnms5D3YQ=="
+      "integrity": "sha1-bRX7qITAhnnA136I53WegR4H+kE="
     },
     "yallist": {
       "version": "3.0.3",