Only pull in 'postgres_backend' instead of 'postgres'

[aumetra]

When used with diesel-async, this crate enables the postgres feature on diesel which causes it to pull in libpq-sys, while postgres_backend suffices for this crate

[weiznich]

I'm generally ok with this change, but we cannot do that now or in that way. Removing this feature from the default configuration would be a breaking change and we do not plane to release a major diesel_full_text_search version anytime soon.

I would be open for the following alternative approach:

• Add a with-diesel-postgres feature to diesel_full_text_search
• Add that feature as default feature
• Only enable postgres_backend unconditionally for the diesel dependency
• Add a CI job to test without default features

[aumetra]

Yeah, I forgot about the semver implications of this change.
I hope this is how you imagined it, the CI is now using cargo-hack to build a powerset of all features, just so testing in the future is easier (in case features get added).

[weiznich]

👍 Thanks for the update. It looks good now.