Revise bucket policy to enforce tls v1.2 or higher connections

[pricemg]

Bumping from just enforcing connections over HTTPS to ensuring the connection is using at least TLS v1.2 (and therefore inherently using https). This aligns with comments raised in various IT health checks. (see e.g. here for an example implementing the policy).

[github-actions]

Trivy Scan Success

Show Output

```hcl

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Trivy will check the following folders:

</details> #### `Checkov Scan` Success
<details><summary>Show Output</summary>

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Checkov will check the following folders:

CTFLint Scan Success

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Setting default tflint config...
Running tflint --init...
Installing "terraform" plugin...
Installed "terraform" (source: github.com/terraform-linters/tflint-ruleset-terraform, version: 0.5.0)
tflint will check the following folders:

Trivy Scan Success

Show Output

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Trivy will check the following folders:

[dms1981]

LGTM - aligns nicely with AWS guidance.