docs: fix vercel build script (#19090)

amazon linux 2023 doesn't have `amazon-linux-extras` but shoudl have python3.9 by default

docs/vercel_build.sh

@@ -2,7 +2,6 @@
 
 yum -y update
 yum install gcc bzip2-devel libffi-devel zlib-devel wget tar gzip -y
-amazon-linux-extras install python3.8 -y
 
 # install quarto
 wget -q https://github.com/quarto-dev/quarto-cli/releases/download/v1.3.450/quarto-1.3.450-linux-amd64.tar.gz
@@ -11,26 +10,26 @@ export PATH=$PATH:$(pwd)/quarto-1.3.450/bin/
 
 
 # setup python env
-python3.8 -m venv .venv
+python3 -m venv .venv
 source .venv/bin/activate
-python3.8 -m pip install --upgrade pip
-python3.8 -m pip install -r vercel_requirements.txt
+python3 -m pip install --upgrade pip
+python3 -m pip install -r vercel_requirements.txt
 
 # autogenerate integrations tables
-python3.8 scripts/model_feat_table.py
+python3 scripts/model_feat_table.py
 
 # copy in external files
 mkdir docs/templates
 cp ../templates/docs/INDEX.md docs/templates/index.md
-python3.8 scripts/copy_templates.py
+python3 scripts/copy_templates.py
 
 cp ../cookbook/README.md src/pages/cookbook.mdx
 
 wget -q https://raw.githubusercontent.com/langchain-ai/langserve/main/README.md -O docs/langserve.md
-python3.8 scripts/resolve_local_links.py docs/langserve.md https://github.com/langchain-ai/langserve/tree/main/
+python3 scripts/resolve_local_links.py docs/langserve.md https://github.com/langchain-ai/langserve/tree/main/
 
 wget -q https://raw.githubusercontent.com/langchain-ai/langgraph/main/README.md -O docs/langgraph.md
-python3.8 scripts/resolve_local_links.py docs/langgraph.md https://github.com/langchain-ai/langgraph/tree/main/
+python3 scripts/resolve_local_links.py docs/langgraph.md https://github.com/langchain-ai/langgraph/tree/main/
 
 # render
 quarto render docs/