fix: Remove AWS credentials action, install AWS CLI directly for R2 (#408)

The aws-actions/configure-aws-credentials action doesn't work with
Cloudflare R2 as it tries to use AWS STS. Instead, install AWS CLI
directly and use environment variables for R2 credentials.

Author: shivasurya

.github/workflows/stdlib-r2-upload.yml

@@ -42,12 +42,12 @@ jobs:
           python3.12 --version
           python3.14 --version
 
-      - name: Configure AWS CLI for R2
-        uses: aws-actions/configure-aws-credentials@v4
-        with:
-          aws-access-key-id: ${{ secrets.R2_ACCESS_KEY_ID }}
-          aws-secret-access-key: ${{ secrets.R2_SECRET_ACCESS_KEY }}
-          aws-region: auto
+      - name: Install AWS CLI
+        run: |
+          curl "https://awscli.amazonaws.com/awscli-exe-linux-x86_64.zip" -o "awscliv2.zip"
+          unzip -q awscliv2.zip
+          sudo ./aws/install --update
+          aws --version
 
       - name: Generate and upload stdlib registries
         env: