Remove the mongo driver (#3099)

* kills mongo

* changelog

* more refeences to mongo needed to go

tox.ini

@@ -39,23 +39,6 @@ passenv =
 commands =
     pytest
 
-[testenv:mongo]
-description = Run pytest with MongoDB backend
-whitelist_externals =
-    pytest
-extras = voice, test, mongo
-setenv =
-    RED_STORAGE_TYPE=mongo
-passenv =
-    RED_MONGO_URI
-    RED_MONGO_HOST
-    RED_MONGO_PORT
-    RED_MONGO_USER
-    RED_MONGO_PASSWORD
-    RED_MONGO_DATABASE
-commands =
-    pytest
-
 [testenv:docs]
 description = Attempt to build docs with sphinx-build
 whitelist_externals =
@@ -66,7 +49,7 @@ setenv =
     # Prioritise make.bat over any make.exe which might be on PATH
     PATHEXT=.BAT;.EXE
 basepython = python3.7
-extras = docs, mongo
+extras = docs
 commands =
     sphinx-build -d "{toxworkdir}/docs_doctree" docs "{toxworkdir}/docs_out/html" -W -bhtml
     sphinx-build -d "{toxworkdir}/docs_doctree" docs "{toxworkdir}/docs_out/linkcheck" -W -blinkcheck