fix: Populate the protocol version of the original request to the ups…

[zhl11b]

Description

fix: Populate the protocol version of the original request to the ups…
If the version is not passed, upstream may use the default version, leading to inconsistent behavior or compatibility issues.

Checklist

• I have explained the need for this PR and the problem it solves
• I have explained the changes or the new features added to this PR
• I have added tests corresponding to this change
• I have updated the documentation to reflect this change
• I have verified that this change is backward compatible (If not, please discuss on the APISIX mailing list first)

[Baoyuantop]

There are no test cases for this modification.

[Baoyuantop]

Hi @zhl11b, following up on the previous review comments. Please let us know if you have any updates. Thank you.

[moonming]

Hi @zhl11b, thank you for submitting this!

I have a few concerns with the current state of this PR:

1. Missing context: There's no associated issue describing the problem this fixes. Could you share the specific scenario where you encountered this issue?

2. No test coverage: The single-line change to ext-plugin-post-resp.lua doesn't have any accompanying tests to verify the fix and prevent regression.

3. Unclear impact: Without a clear description of the bug and steps to reproduce, it's difficult to validate whether this change is correct and doesn't introduce side effects.

Since this has been inactive for several months, I'm going to close this PR. If you're still experiencing the issue, please:

1. Open an issue first describing the problem with reproduction steps
2. Submit a new PR with the fix and test cases that demonstrate the before/after behavior

Thanks for your interest in improving APISIX!