ci: make isort is red on main (pcapkit/protocols/schema/schema.py) #757

Describe the bug

make isort is red on main: pcapkit/protocols/schema/schema.py has imports isort wants reformatted.
CONTRIBUTING.md lists make isort among the checks a contributor is asked to run, so it currently fails
on a clean checkout through no fault of the change under test.

Reproduction

On 73f09aecb:

$ python -m isort --check-only --diff pcapkit/protocols/schema/schema.py
ERROR: pcapkit/protocols/schema/schema.py Imports are incorrectly sorted and/or formatted.
@@ -10,19 +10,22 @@
-from pcapkit.corekit.fields.misc import ConditionalField, ForwardMatchField, PayloadField
+from pcapkit.corekit.fields.misc import (ConditionalField, ForwardMatchField,
+                                         PayloadField)

Expected behavior

Either the file is reformatted so make isort is clean, or isort's configuration is adjusted to accept the
single-line form. The one-line import is 89 characters, and the project's own line-too-long threshold is
120 — so isort's wrap width appears to disagree with the linter's, which is the more likely root cause and
the more durable fix.

System information

• OS Version: Linux 5.10 (Amazon Linux 2 int)
• Python Version: 3.14.7
• Python Implementation: CPython
• pcapkit Version: checkout at 73f09aecb

Additional context

Found while cross-reviewing #752 — identical on both trees, so unrelated to that PR. Worth noting it is not
alone: lint.yml's own header records bandit, mypy, vermin and pylint all exiting non-zero, which
is why none of them gates a merge (see #753 for that comment's figures having drifted). So this is one
instance of a broader "the documented checks do not pass on main" situation, and fixing it in isolation
does not make make lint green.