Require Roave Security Advisories as `dev-latest`

[tyrann0us]

Please check if the PR fulfills these requirements

• [x] The commit message follows our guidelines
• [ ] Tests for the changes have been added (for bug fixes/features)
• [ ] Docs have been added/updated (for bug fixes/features)

What kind of change does this PR introduce? (Bug fix, feature, docs update, ...) Chore

What is the current behavior? (You can also link to an open issue here) roave/security-advisories is required with dev-master constraint.

What is the new behavior (if this is a feature change)? roave/security-advisories is required with dev-latest constraint.

Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?) No

Other information: From https://github.com/Roave/SecurityAdvisories:

Simply add "roave/security-advisories": "dev-latest" to your composer.json "require-dev" section […]