ext: Update pybind11 to v2.8.1

Change-Id: Ia1c7081377f53fd470addf35526f8b28a949a7b0
Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/52523
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Gabe Black <gabe.black@gmail.com>

ext/pybind11/setup.cfg

@@ -20,6 +20,7 @@ classifiers =
     Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
+    Programming Language :: Python :: 3.10
     License :: OSI Approved :: BSD License
     Programming Language :: Python :: Implementation :: PyPy
     Programming Language :: Python :: Implementation :: CPython
@@ -37,17 +38,6 @@ zip_safe = False
 [bdist_wheel]
 universal=1
 
-[check-manifest]
-ignore =
-    tests/**
-    docs/**
-    tools/**
-    include/**
-    .*
-    pybind11/include/**
-    pybind11/share/**
-    CMakeLists.txt
-
 
 [flake8]
 max-line-length = 99
@@ -61,25 +51,6 @@ ignore =
     # Black conflict
     W503, E203
 
-[mypy]
-files = pybind11
-python_version = 2.7
-warn_unused_configs = True
-
-# Currently (0.800) identical to --strict
-disallow_any_generics = True
-disallow_subclassing_any = True
-disallow_untyped_calls = True
-disallow_untyped_defs = True
-disallow_incomplete_defs = True
-check_untyped_defs = True
-disallow_untyped_decorators = True
-no_implicit_optional = True
-warn_redundant_casts = True
-warn_unused_ignores = True
-warn_return_any = True
-no_implicit_reexport = True
-strict_equality = True
 
 [tool:pytest]
 timeout = 300