build(deps): Update segno requirement from >=1.6 to >=1.6.6 in /requirements

[dependabot]

Updates the requirements on segno to permit the latest version.

Release notes

Sourced from segno's releases.

1.6.6

• Fixed man page directory. This issue was introduced by mistake in the 1.6.4/1.6.5 release and was reported by Johannes Kastl and Michał Górny

Changelog

Sourced from segno's changelog.

1.6.6 -- 2025-03-12

• Fixed man page directory. This issue was introduced by mistake in the 1.6.4/1.6.5 release and was reported by Johannes Kastl <https://github.com/kastl-ars>_ and Michał Górny <https://github.com/mgorny>_

1.6.5 -- 2025-03-11

• Fixed release notes / aligned changelog to the mistake of skipping two minor releases

1.6.4 -- 2025-03-11

• Fixed packaging: include man page, source distribution did not contain all relevant files such as docs and test suite.
• Moved man page to the correct directory
• Fixed PDF creation: PR [#144](https://github.com/heuer/segno/issues/144) <https://github.com/heuer/segno/pull/144>_ and PR [#145](https://github.com/heuer/segno/issues/145) <https://github.com/heuer/segno/pull/145>_ provided by Mathias Winkel <https://github.com/dasmy>_
• Merged PR [#143](https://github.com/heuer/segno/issues/143) <https://github.com/heuer/segno/pull/143>_ (typo in docs) provided by Marek Madejski <https://github.com/TrangOul>_

1.6.2 - 1.6.3 -- not released

• Release 1.6.2 was labeled as 1.6.4 by mistake

1.6.1 -- 2024-02-08

• Switched from setuptools to flit for setup
• Updated test suite to work with musl based distributions

1.6.0 -- 2023-11-28

• Dropped Python 2.7 support
• Removed dependency on pkg_resources. Segno uses importlib.metadata to provide plugins. For Python versions < 3.10 this introduces a dependency on importlib-metadata.

1.5.3 -- 2023-10-25

• Merged PR [#124](https://github.com/heuer/segno/issues/124) <https://github.com/heuer/segno/pull/124>_ implemented by missionfloyd <https://github.com/missionfloyd>_: Remove the trailing dot of latitude/longitude information.
• Merged PR [#125](https://github.com/heuer/segno/issues/125) <https://github.com/heuer/segno/pull/125>_ implemented by

... (truncated)

Commits

• 9b67a3f Merge release branch release-1.6.6
• 8da7980 Preparing release 1.6.6
• adaf2a8 Moved the man page to the correct location, closes #146
• 3bbff5a Incremented development version
• b481a3d Merge release branch release-1.6.5
• e2b59ad Preparing release 1.6.5
• 1c69f24 Fixed CHANGES
• 2fa570f Incremented development version
• e050093 Merge release branch release-1.6.4
• e2e88c6 Preparing release 1.6.4
• Additional commits viewable in compare view

[ilyautov]

@dependabot rebase