style: streamline flake8 options, and ignore long lines again

We used to ignore E501, and not ignoring it spews lots of errors
that I want to continue hiding unless we really plan to fix them.

.flake8

@@ -1,7 +1,3 @@
-# NOTE: This is actually ignored by flake8 in pre-commit for some
-# reason but it will get used in editors.  How to make flake8 read it?
-# Who knows? flake8 is a mystery.
-
 [flake8]
-max-line-length = 120
-extend-ignore = E203,E704
+max-line-length = 88
+extend-ignore = E203,E501,E704

.pre-commit-config.yaml

@@ -32,7 +32,6 @@ repos:
         stages: [commit]
 -   repo: https://github.com/pycqa/flake8
     # do flake8 last to avoid duplicate reports
-    rev: 5.0.4
+    rev: 7.0.0
     hooks:
     - id: flake8
-      args: ["--max-line-length=120", "--extend-ignore=E203,E704"]