Bump lodash from 4.17.15 to 4.17.19

Bumps [lodash](https://github.com/lodash/lodash) from 4.17.15 to 4.17.19.
- [Release notes](https://github.com/lodash/lodash/releases)
- [Commits](lodash/lodash@4.17.15...4.17.19)

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

Author: dependabot[bot]

package.json

@@ -61,7 +61,7 @@
     "gatsby-source-filesystem": "2.1.48",
     "gatsby-source-ghost": "4.0.4",
     "gatsby-transformer-sharp": "2.3.16",
-    "lodash": "4.17.15",
+    "lodash": "4.17.19",
     "prismjs": "^1.20.0",
     "react": "16.13.0",
     "react-dom": "16.13.0",

yarn.lock

@@ -8988,6 +8988,11 @@ lodash@4.17.15:
   resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.15.tgz#b447f6670a0455bbfeedd11392eff330ea097548"
   integrity sha512-8xOcRHvCjnocdS5cpwXQXVzmmh5e5+saE2QGoeQmbKmRS6J3VQppPOIt0MnmE+4xlZoumy0GPG0D0MVIQbNA1A==
 
+lodash@4.17.19:
+  version "4.17.19"
+  resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.19.tgz#e48ddedbe30b3321783c5b4301fbd353bc1e4a4b"
+  integrity sha512-JNvd8XER9GQX0v2qJgsaN/mzFCNA5BRe/j8JN9d+tWyGLSodKQHKFicdwNYzWwI3wjRnaKPsGj1XkBjx/F96DQ==
+
 lodash@^4.11.1, lodash@^4.15.0, lodash@^4.16.4, lodash@^4.17.10, lodash@^4.17.11, lodash@^4.17.12, lodash@^4.17.14, lodash@^4.17.15, lodash@^4.17.19, lodash@^4.17.20, lodash@^4.17.4, lodash@^4.17.5, lodash@^4.3.0:
   version "4.17.21"
   resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.21.tgz#679591c564c3bffaae8454cf0b3df370c3d6911c"