chore(lambda-nodejs): bump pnpm version in Dockerfile for AWS Lambda Node.js

Author: HiroshiIgarash

packages/aws-cdk-lib/aws-lambda-nodejs/lib/Dockerfile

@@ -7,7 +7,7 @@ FROM $IMAGE
 RUN npm install --global yarn@1.22.5
 
 # Install pnpm
-RUN npm install --global pnpm@7.30.5
+RUN npm install --global pnpm@8.15.9
 
 # Install bun
 RUN npm install --global bun@1.1.30