[v0.20.x-branch] Backport #11098: build: bump Go language to 1.25.13 and toolchain to 1.26.6 - #11103

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, actions/upload-artifact@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Cache reservation failed: cache write denied: token has no writable scopes

Unexpected input(s) 'model', valid inputs are ['trigger_phrase', 'assignee_trigger', 'label_trigger', 'base_branch', 'branch_prefix', 'branch_name_template', 'allowed_bots', 'allowed_non_write_users', 'include_comments_by_actor', 'exclude_comments_by_actor', 'prompt', 'settings', 'anthropic_api_key', 'claude_code_oauth_token', 'anthropic_federation_rule_id', 'anthropic_organization_id', 'anthropic_service_account_id', 'anthropic_workspace_id', 'anthropic_oidc_audience', 'github_token', 'use_bedrock', 'use_vertex', 'use_foundry', 'claude_args', 'additional_permissions', 'use_sticky_comment', 'classify_inline_comments', 'use_commit_signing', 'ssh_signing_key', 'bot_id', 'bot_name', 'track_progress', 'include_fix_links', 'path_to_claude_code_executable', 'path_to_bun_executable', 'display_report', 'show_full_output', 'plugins', 'plugin_marketplaces']

⚠️ SECURITY WARNING: Bypassing write permission check for ziggie1984 due to allowed_non_write_users='*'. This should only be used for workflows with very limited permissions.