ci(deps): bump aws-actions/configure-aws-credentials from 5 to 6

v6 moves the action runtime to Node 24, which GitHub-hosted
`ubuntu-latest` runners support natively. The v6 changes are
additive (transitive tag keys, corrected role-chaining outputs);
existing inputs are byte-identical between v5 and v6.

Tag: https://github.com/aws-actions/configure-aws-credentials/tree/v6
Changelog: https://github.com/aws-actions/configure-aws-credentials/blob/main/CHANGELOG.md

Author: tony

.github/workflows/docs.yml

@@ -79,7 +79,7 @@ jobs:
 
       - name: Configure AWS Credentials
         if: env.PUBLISH == 'true'
-        uses: aws-actions/configure-aws-credentials@v5
+        uses: aws-actions/configure-aws-credentials@v6
         with:
           role-to-assume: ${{ secrets.LIBTMUX_DOCS_ROLE_ARN }}
           aws-region: us-east-1