Make pylint parallel (quantumlib#5144)

On my local machine this took pylint from 3 minutes to less than one.

Author: dabacon

check/pylint

@@ -14,4 +14,4 @@ cd "$(git rev-parse --show-toplevel)"
 CIRQ_MODULES=$(env PYTHONPATH=. python dev_tools/modules.py list --mode package-path)
 
 # Add dev_tools to $PYTHONPATH so that pylint can find custom checkers
-env PYTHONPATH=dev_tools pylint --rcfile=dev_tools/conf/.pylintrc "$@" $CIRQ_MODULES dev_tools examples
+env PYTHONPATH=dev_tools pylint --jobs=0 --rcfile=dev_tools/conf/.pylintrc "$@" $CIRQ_MODULES dev_tools examples

check/pylint-changed-files

@@ -66,4 +66,4 @@ echo "Found ${num_changed} lintable files associated with changes." >&2
 if [ "${num_changed}" -eq 0 ]; then
     exit 0
 fi
-env PYTHONPATH=dev_tools pylint --rcfile=dev_tools/conf/.pylintrc "${changed[@]}"
+env PYTHONPATH=dev_tools pylint --jobs=0 --rcfile=dev_tools/conf/.pylintrc "${changed[@]}"

dev_tools/bash_scripts_test.py

@@ -638,7 +638,7 @@ def test_pylint_changed_files_file_selection(tmpdir_factory):
     )
 
     intercepted_prefix = (
-        'INTERCEPTED env PYTHONPATH=dev_tools pylint --rcfile=dev_tools/conf/.pylintrc '
+        'INTERCEPTED env PYTHONPATH=dev_tools pylint --jobs=0 --rcfile=dev_tools/conf/.pylintrc '
     )
 
     result = run(