Suppress pkg_resources deprecation warning on Alpine Docker builds

[fresh3nough]

Issue

Fixes #10065

Description

Building AWS CLI v2 from source on Alpine Docker with setuptools >= 81 produces a UserWarning at runtime:

PyInstaller/loader/pyimod02_importers.py:384: UserWarning: pkg_resources is deprecated as an API. See https://setuptools.pypa.io/en/latest/pkg_resources.html. The pkg_resources package is slated for removal as early as 2025-11-30. Refrain from using this package or pin to Setuptools<81.

This change addresses two root causes:

1. Removes the outdated pkg_resources.py2_warn hidden import from exe/pyinstaller/hook-awscli.py. This hidden import was a workaround for pypa/setuptools#1963, which has been resolved upstream in PyInstaller 5.5+ (see pyinstaller/pyinstaller#6952). The py2_warn module was removed from setuptools around version 49.

2. Adds a PyInstaller runtime hook (pyi_rth_pkg_resources_warning.py) that suppresses the UserWarning emitted by setuptools >= 81 when pkg_resources is imported at runtime. This hook is registered in both aws.spec and aws_completer.spec.

Steps to Reproduce the Issue

Build the CLI on Alpine Docker using the following Dockerfile:

FROM alpine:latest

WORKDIR /aws-cli-sourcecode

RUN apk upgrade --no-cache && \
    apk add --update --no-cache bash ca-certificates musl-dev curl jq htop groff build-base libffi-dev cmake git && \
    apk add python3-dev python3 && \
    git clone --recursive --depth 1 --branch v2 --single-branch https://github.com/aws/aws-cli.git /aws-cli-sourcecode

RUN python -m venv venv && \
    . venv/bin/activate && \
    python3 -m ensurepip && \
    ln -s /usr/bin/pip3 /usr/bin/pip && \
    pip install setuptools && \
    scripts/installers/make-exe && \
    unzip -q dist/awscli-exe.zip && \
    aws/install --bin-dir /aws-cli-bin && \
    /aws-cli-bin/aws --version

Before this fix, the final command outputs:

PyInstaller/loader/pyimod02_importers.py:384: UserWarning: pkg_resources is deprecated as an API...
aws-cli/2.x.x Python/3.x.x Linux/...

Steps to Verify the Fix

Build with the same Dockerfile, replacing the git clone branch with this PR branch. The warning should no longer appear in the output of /aws-cli-bin/aws --version.

Changes

• exe/pyinstaller/hook-awscli.py: Removed pkg_resources.py2_warn from hidden imports
• exe/pyinstaller/pyi_rth_pkg_resources_warning.py: New runtime hook to filter the deprecation warning
• exe/pyinstaller/aws.spec: Added runtime hook reference
• exe/pyinstaller/aws_completer.spec: Added runtime hook reference