[deps] Update pelican-sitemap requirement from ~=1.2.0 to ~=1.2.1

Updates the requirements on [pelican-sitemap](https://github.com/pelican-plugins/sitemap) to permit the latest version.
- [Release notes](https://github.com/pelican-plugins/sitemap/releases)
- [Changelog](https://github.com/pelican-plugins/sitemap/blob/main/CHANGELOG.md)
- [Commits](pelican-plugins/sitemap@1.2.0...1.2.1)

---
updated-dependencies:
- dependency-name: pelican-sitemap
  dependency-version: 1.2.1
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements.txt

@@ -2,7 +2,7 @@ pelican~=4.11.0
 pelican-jinja2content~=1.0.1
 pelican-minify~=2.0.0
 minify-html<=0.15.0
-pelican-sitemap~=1.2.0
+pelican-sitemap~=1.2.1
 typogrify~=2.1.0
 pylinkvalidator
 openwisp-utils[qa]