Merge pull request #199 from jonesbusy/feature/mkdocs-1.6

Update mkdocs to 1.6

requirements.txt

@@ -1,7 +1,7 @@
 # The following are something akin to peer dependencies. They are represented
 # as ranges in order to support interoperability with other mkdocs plugins or
 # packages that might otherwise exist in an adopter's environment.
-mkdocs>=1.5
+mkdocs>=1.6
 Markdown>=3.2,<3.4
 
 # The following are more akin to direct dependencies. Each line represents one