Replace template1 with postgres:///template1

[hos]

Description

Performance impact

Security impact

Checklist

• My code matches the project's code style and yarn lint:fix passes.
• I've added tests for the new feature, and yarn test passes.
• I have detailed the new feature in the relevant documentation.
• I have added this feature to 'Pending' in the RELEASE_NOTES.md file (if one exists).
• If this is a breaking change I've explained why.

[benjie]

Awesome! Thanks for doing this!

By the way, the protocol is postgres://user:pass@host:port/dbname; so postgres:///dbname essentially means "use defaults for user, pass, host and port" since that section (between second and third slash) is omitted entirely).