Correct default http_version from float to string

[downingar]

Proposed changes

This is a simple fix that corrects the value of the default http_version to a string, which is what is required/expected by Nginx itself.

Checklist

Before creating a PR, run through this checklist and mark each as complete:

• I have read the CONTRIBUTING document.
• I have added Molecule tests that prove my fix is effective or that my feature works.
• I have checked that any relevant Molecule tests pass after adding my changes.
• I have updated any relevant documentation (defaults/main/*.yml, README.md and CHANGELOG.md).

I'll admit to being lazy and not running any Molecule tests here, though one should probably be added to catch this. I have very little experience with Molecule, but I'm willing to add it if someone can give me a few hints on where to look and what to do.

[github-actions]

✅ All required contributors have signed the F5 CLA for this PR. Thank you!
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[downingar]

I have hereby read the F5 CLA and agree to its terms