HTTP Strict Transport Security (HSTS) Max- Age Value Too Low

[amirbey]

Background (Optional)

as per auth scanned report, hsts max-age should be increased

Acceptance Criteria

• [x] HSTS max-age updated (max-age=31536000)
• [x] Change made live via deploy of Federalist

After evaluating, edit this part:

Level of effort - low

Implementation outline (if higher than "low" effort):

• [ ] <TODO>

[amirbey]

PR - https://github.com/18F/federalist/pull/3639