flake8: fix warnings with newer versions

The flake8 version hasn't updated properly due the uv.lock file
being out of date.  Fix newer warnings before unwedging that.

We have a lot of B042 errors that probably should be fixed by reworking
the code, but for now suppress them since we've been doing this for a
long time in repo.
error.py:25:5: B042 Exception class with `__init__` should pass all args to `super().__init__()` to work in edge cases of `pickle` and `copy.copy()`. It should also not take any kwargs.

The only other warning is fairly simple:
subcmds/sync.py:1154:9: B018 Found useless Call expression. Consider either assigning it to a variable or removing it.

Change-Id: I532000a66a5d8493a490fa30080b137aff5f706e
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/655844
Tested-by: Mike Frysinger <vapier@google.com>
Commit-Queue: Mike Frysinger <vapier@google.com>
Reviewed-by: Gavin Mak <gavinmak@google.com>

.flake8

@@ -26,6 +26,9 @@ per-file-ignores =
     tests/e2e/test_workflows.py: IMR241,
     tests/test_subcmds_sync.py: IMR241,
 extend-ignore =
+    # B042: Exception class with __init__ should pass all args to super().__init__()
+    # We should fix this by reworking our exception classes.
+    B042,
     # E203: Whitespace before ':'
     # See https://github.com/PyCQA/pycodestyle/issues/373
     E203,

subcmds/sync.py

@@ -1199,7 +1199,7 @@ later is required to fix a server side protocol bug.
         # job at the same time. Then the connection may fail if too many
         # connections are pending and execeeded the socket listening backlog,
         # especially on MacOS.
-        len(cls.get_parallel_context()["sync_dict"])
+        _ = len(cls.get_parallel_context()["sync_dict"])
 
     def _Fetch(self, projects, opt, err_event, ssh_proxy, errors):
         ret = True