Update Bun version to fix proxy handling issues in bun install

[tsubasahonda]

Describe the bug The current version of Bun (v1.2.11) used in claude-code-action has issues with proxy handling that cause bun install to hang when downloading packages, especially large packages, through a proxy. This results in random hangs at "Resolving..." or "Installing..." stages, and "ShortRead" decompression errors in Docker environments. This issue is documented in https://github.com/oven-sh/bun/issues/17793.

To Reproduce Steps to reproduce the behavior:

1. Use claude-code-action with Bun v1.2.11 in an environment behind a proxy
2. Run a workflow that executes bun install
3. Observe the process hanging during package download or resolution
4. See errors like: error: ShortRead decompressing "<package>" to "..."

Expected behavior The bun install command should complete successfully even when running behind a proxy, without hangs or decompression errors.

Screenshots N/A (Error details can be found in the linked issue: https://github.com/oven-sh/bun/issues/17793)

Workflow yml file Standard claude-code-action workflow using default Bun version (v1.2.11) in environments that require proxy configuration.

API Provider

[x] Anthropic First-Party API (default) [ ] AWS Bedrock [ ] GCP Vertex

Additional context

• Current Bun version in claude-code-action: v1.2.11
• The proxy handling issue has been fixed in Bun via PR #19771 (merged on May 21, 2025)

[rekram1-node]

Idk this may still be an issue? https://github.com/oven-sh/bun/issues/17793#issuecomment-3612734566

bun install behind a proxy still seems to hang sometimes without --no-cache