misc: add pyupgrade files/notes (#55490)

.git-blame-ignore-revs

@@ -6,3 +6,5 @@ a11be8fa590ad3d02a903dacb8393336b989a1a6
 08f1431a665aec6586960e78cbfda6da47aa6862
 # misc: apply isort (#52224)
 48470c50c0e9b56e989cfbcdcec433de0cc8479a
+# misc: apply pyupgrade (#55490)
+ff0d3779c024ba3a0109b91d9337aadd06b06788

.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

@@ -43,8 +43,13 @@ isort is used to format the imports, using those parameters:
 
     isort --profile black --line-length 110
 
-There is .pre-commit-config.yaml to use pre-commit to automatically run black and isort
-before commits. (execute `pre-commit install` to install the git hook.)
+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.)
 
 
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