Fix some issues reported by lintian

Fix some issues reported by lintian

• Trim trailing whitespace. (trailing-whitespace)
• Set upstream metadata fields: Bug-Database, Bug-Submit, Repository-Browse. (upstream-metadata-file-is-missing, upstream-metadata-missing-bug-tracking)
• Update standards version to 4.6.1, no changes needed. (out-of-date-standards-version)

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Build and test logs for this branch can be found at https://janitor.debian.net/lintian-fixes/pkg/lua-sql/b81f89d7-c9e8-44e9-9471-e20092de4c3a.

These changes affect the binary packages; see the debdiff

You can also view the diffoscope diff (unfiltered).