parse: Allow use of the wildcard CA in Certificate section

[forfuncsake]

OpenSSH allows the use of an empty CA, known as the wildcard CA in a certificate section. All subsections then apply for certs from any and all CAs.

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[forfuncsake]

@prathmesh-stripe @mbroshi-stripe, as recent contributors to stripe-go, you might be well placed to review this little one? :pray:

[stroopc-stripe]

Hey there! Thank you for your contribution and the time you've invested in this pull request.

After careful consideration, we've made the decision to deprecate this repository. We're planning to integrate its functionality into a larger, internal project that better aligns with our current development goals and infrastructure.

While we won't be merging this specific pull request, you're welcome to fork the repository and add the change there.

We'll be archiving this repository soon, but the code will remain available for reference. If you have any ongoing projects that depend on this repository, we recommend considering alternative solutions or forking the project for your needs.

Once again, thank you for your contribution and understanding. We appreciate your support of open-source software!