Update mkdocs-minify-plugin requirement from ==0.6.* to ==0.7.*

Updates the requirements on [mkdocs-minify-plugin](https://github.com/byrnereese/mkdocs-minify-plugin) to permit the latest version.
- [Release notes](https://github.com/byrnereese/mkdocs-minify-plugin/releases)
- [Commits](byrnereese/mkdocs-minify-plugin@0.6.0...0.7.0)

---
updated-dependencies:
- dependency-name: mkdocs-minify-plugin
  dependency-type: direct:production
...

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

requirements/documentation.txt

@@ -1,6 +1,6 @@
 # Documentation
 # -----------------------
 mkdocs-bootswatch>=1,<2
-mkdocs-minify-plugin==0.6.*
+mkdocs-minify-plugin==0.7.*
 pygments>=2.5,<3
 pymdown-extensions>=10,<11