Bump secure_headers from 6.5.0 to 6.7.0 (#886)

Bumps [secure_headers](https://github.com/twitter/secureheaders) from 6.5.0 to 6.7.0.
- [Release notes](https://github.com/twitter/secureheaders/releases)
- [Changelog](https://github.com/github/secure_headers/blob/main/CHANGELOG.md)
- [Commits](github/secure_headers@v6.5.0...v6.7.0)

---
updated-dependencies:
- dependency-name: secure_headers
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Gemfile.lock

@@ -425,7 +425,7 @@ GEM
     sawyer (0.9.2)
       addressable (>= 2.3.5)
       faraday (>= 0.17.3, < 3)
-    secure_headers (6.5.0)
+    secure_headers (6.7.0)
     shoulda-matchers (6.4.0)
       activesupport (>= 5.2.0)
     simplecov (0.22.0)