Update requirements.txt

docs/requirements.txt

@@ -1,8 +1,8 @@
 git+git://github.com/g-provost/lightgallery-markdown#egg=lightgallery
+git+https://github.com/squidfunk/mkdocs-material
 markdown==3.3.4
 mkdocs-awesome-pages-plugin==2.5.0
 mkdocs-git-revision-date-localized-plugin==0.9.2
-mkdocs-macros-plugin==0.5.5
 mkdocs-material-extensions==1.0.1
 mkdocs-material==7.1.8
 mkdocs-minify-plugin==0.4.0