misc: add pyupgrade files/notes (#55519)

.git-blame-ignore-revs

@@ -4,3 +4,5 @@
 86d946adcdc784693d733131c2aecafc6caa8cbb
 # misc: remove unicode prefixed strings
 a265c6267e75c831b8294a760f94b9d6cffb92ea
+# misc: apply pyupgrade
+7bc0fcadffd16564cc200cb2f32fae80b3c3a5cf

.pre-commit-config.yaml

@@ -11,3 +11,8 @@ repos:
     hooks:
     - id: isort
       args: ['--profile', 'black', '--line-length', '110']
+-   repo: https://github.com/asottile/pyupgrade
+    rev: v2.20.0
+    hooks:
+    - id: pyupgrade
+      args: ['--keep-percent-format', '--py37-plus']

README

@@ -83,6 +83,14 @@ isort is used to format the imports, using those parameter:
 
     isort --profile black --line-length 110
 
+pyupgrade is used to automatically upgrade syntax, using those parameters:
+
+    pyupgrade --keep-percent-format --py37-plus
+
+There is .pre-commit-config.yaml to use pre-commit to automatically run black,
+isort and pyupgrade before commits. (execute `pre-commit install` to install
+the git hook.)
+
 Support
 =======
 

tox.ini

@@ -113,8 +113,7 @@ skip_install = true
 deps =
   pre-commit
 commands =
-  pre-commit run black --all-files --show-diff-on-failure
-  pre-commit run isort --all-files --show-diff-on-failure
+  pre-commit run --all-files --show-diff-on-failure
 
 [pytest]
 filterwarnings =