Fix pyproject.toml license classifier deprecation (#14592)

Gets rid of the 'deprecated' warnings that pop up multiple times during
build/install

Bumps setuptools requirement to accept the new license declaration
format

### Summary
Just a tiny PR, no change to API or code or anything. The license itself
is as before, it just changes the manner in which it is declared -- as
recommended by the PyPA guidelines
https://packaging.python.org/en/latest/guides/writing-pyproject-toml/#license

I tried to find any issue related to this but found none. And I guess
not worth it creating one

### Test plan
Since this does not change any of the code, I just tested that the
package can be installed/built as before via `./install_executorch.sh`,
and that the deprecation warnings vanish

Author: tmi

pyproject.toml

@@ -1,9 +1,10 @@
 [build-system]
 requires = [
   "cmake>=3.29,<4.0.0",  # For building binary targets in the wheel. 4.0.0 breaks third-party CMake build so temporarily pin the version.
+  "packaging>=24.2", # Lower bound required by setuptools
   "pip>=23",  # For building the pip package.
   "pyyaml",  # Imported by the kernel codegen tools.
-  "setuptools>=63",  # For building the pip package contents.
+  "setuptools>=77.0.3",  # For building the pip package contents.
   "wheel",  # For building the pip package archive.
   "zstd",  # Imported by resolve_buck.py.
   "certifi",  # Imported by resolve_buck.py.
@@ -21,7 +22,8 @@ readme = "README-wheel.md"
 authors = [
   {name="PyTorch Team", email="[email protected]"},
 ]
-license = {file = "LICENSE"}
+license = "BSD-3-Clause"
+license-files = ["LICENSE"]
 keywords = ["pytorch", "machine learning"]
 # PyPI package information.
 classifiers = [
@@ -33,7 +35,6 @@ classifiers = [
     "Intended Audience :: Developers",
     "Intended Audience :: Education",
     "Intended Audience :: Science/Research",
-    "License :: OSI Approved :: BSD License",
     "Topic :: Scientific/Engineering",
     "Topic :: Scientific/Engineering :: Mathematics",
     "Topic :: Scientific/Engineering :: Artificial Intelligence",

requirements-dev.txt

@@ -1,9 +1,10 @@
 # Pip packages needed to build from source. Mainly for development of ExecuTorch.
 
 cmake>=3.29, <4.0.0  # For building binary targets in the wheel.
+packaging>=24.2 # Lower bound required by setuptools
 pip>=23  # For building the pip package.
 pyyaml  # Imported by the kernel codegen tools.
-setuptools>=63  # For building the pip package contents.
+setuptools>=77.0.3  # For building the pip package contents.
 wheel  # For building the pip package archive.
 zstd  # Imported by resolve_buck.py.
 certifi  # Imported by resolve_buck.py.