Remove unnecessary constraints

[debian-janitor]

Remove unnecessary constraints.

This merge proposal was created automatically by the Janitor bot.
For more information, including instructions on how to disable
these merge proposals, see https://janitor.debian.net/scrub-obsolete.

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Build and test logs for this branch can be found at
https://janitor.debian.net/scrub-obsolete/pkg/postgresql-unit/3e3b2b71-c83f-402a-a1d5-7c830106305f.

These changes have no impact on the binary debdiff.

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[df7cb]

Hi,
while the actual change made is good, the message "Not a Debian package" in debian/changelog is wrong.

Thanks for running the Janitor!