Fix mxeval installation in mbxp_evaluation setup

The mxeval package was failing to install due to two issues with
newer pip/setuptools versions:

1. pkg_resources has been removed from setuptools>=82. When pip
   uses build isolation (default), it installs latest setuptools
   which no longer includes pkg_resources, causing mxeval setup.py
   to fail.

2. The entry_point in mxeval setup.py is missing the required
   callable suffix (:main), which newer pip versions enforce.

Fix by:
- Pinning mxeval to a known-good commit (e09974f)
- Patching the broken entry_point after cloning
- Using --no-build-isolation to use existing setuptools

Author: Adam Stachowicz

examples/text-generation/mbxp_evaluation/setup.sh

@@ -5,9 +5,13 @@
 
 set -xe
 
+MXEVAL_COMMIT="e09974f"
+
 apt-get update
 git clone https://github.com/amazon-science/mxeval.git
-pip install -e mxeval
+cd mxeval && git checkout ${MXEVAL_COMMIT} && cd ..
+sed -i 's/evaluate_functional_correctness = mxeval.evaluate_functional_correctness"/evaluate_functional_correctness = mxeval.evaluate_functional_correctness:main"/' mxeval/setup.py
+pip install -e mxeval --no-build-isolation
 sed -i 's/npx tsc/tsc/g' mxeval/mxeval/execution.py
 cp evaluation_setup/ubuntu.sh mxeval/language_setup/ubuntu.sh
 PATH="$HOME/.rbenv/bin:$PATH" bash mxeval/language_setup/ubuntu.sh