build(deps): bump safe-buffer from 5.1.2 to 5.2.1

Bumps [safe-buffer](https://github.com/feross/safe-buffer) from 5.1.2 to 5.2.1.
- [Commits](feross/safe-buffer@v5.1.2...v5.2.1)

---
updated-dependencies:
- dependency-name: safe-buffer
  dependency-version: 5.2.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

package.json

@@ -11,7 +11,7 @@
   ],
   "repository": "jshttp/basic-auth",
   "dependencies": {
-    "safe-buffer": "5.1.2"
+    "safe-buffer": "5.2.1"
   },
   "devDependencies": {
     "eslint": "5.6.0",