[dendrite] Bump and correct postgresql subchart config

[wrmilling]

Description of the change

• Bumped the PostgreSQL subchart version and image tag
• Corrected persistence definition in values.yaml

Benefits

Newest revision of PostgreSQL and correct values.yaml.

Possible drawbacks

N/A

Applicable issues

N/A

Additional information

N/A

Checklist

• [X] Title of the PR starts with chart name (e.g. [home-assistant])
• [X] Chart version bumped in Chart.yaml according to semver.
• [X] 1Chart artifacthub.io/changes changelog annotation has been updated in Chart.yaml. See Artifact Hub documentation for more info.
• [X] Variables have been documented in the values.yaml file.

[wrmilling]

@Jonnobrow Let me know if you have any qualms with the minor change here, tested via wrmilling-charts in my cluster

[wrmilling]

Looks like this will have long term issues with #1572, only problem I saw is that you have to specify every component's database connection instead of being able to just supply username/password in a simplified configuration in the current form. Might be fodder for a future PR.