skip venv, .downloads and third_party with isort and pyink. (#8)

Manually tested that format.sh works as intended in my local setup.

BUG=fix dev workflow

Author: advaitjain

format.sh

@@ -18,5 +18,5 @@
 
 set -ex
 
-pyink --pyink-use-majority-quotes --pyink-indentation 2 ./
-isort --profile google --multi-line 7 --skip .downloads ./
+pyink --pyink-use-majority-quotes --pyink-indentation 2 --extend-exclude third_party --extend-exclude .downloads ./
+isort --profile google --multi-line 7 --skip .downloads ./ --skip venv --skip third_party