build(deps): update rich-argparse requirement from <1.5,>=1 to >=1,<1.6

Updates the requirements on [rich-argparse](https://github.com/hamdanal/rich-argparse) to permit the latest version.
- [Release notes](https://github.com/hamdanal/rich-argparse/releases)
- [Changelog](https://github.com/hamdanal/rich-argparse/blob/main/CHANGELOG.md)
- [Commits](hamdanal/rich-argparse@v1.0.0...v1.5.0)

---
updated-dependencies:
- dependency-name: rich-argparse
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

requirements/base.txt

@@ -4,7 +4,7 @@ markdownify>=0.11,<0.13
 Mastodon.py>=1.8.1,<1.9
 orjson>=3.8,<3.11
 packaging>=20,<25
-rich_argparse>=1,<1.5
+rich_argparse>=1,<1.6
 python-frontmatter>=1,<2
 requests>=2.31,<3
 typing-extensions>=4,<5 ; python_version < '3.11'