Fix lint command (#96)

Because there are git submodules now doing `black .` will change files inside those submodules, which is not what we want.
Breaking up the commands to only affect the code we want to lint.

Author: giovanni-guidini

Makefile

@@ -2,5 +2,7 @@ name ?= codecovcli
 
 lint:
 	pip install black==22.3.0 isort==5.10.1
-	black .
-	isort --profile black .
+	black codecov_cli/**
+	isort --profile black codecov_cli/**
+	black tests/**
+	isort --profile black tests/**