feat(build-curl-h3): auto-trigger on tag push

[tzssangglass]

During the process of submitting a PR for lua-nginx-module earlier, I encountered a CI failure: https://github.com/openresty/lua-nginx-module/actions/runs/26863098901/job/79220859392

After conducting an investigation, I found that it was due to

TEST 2 (lua_need_request_body off) in HTTP/3 mode, curl times out:

WARNING: t/031-post-args.t TEST 2: lua_need_request_body off - command "curl -i -H User-Agent:
-H Accept: -H Host: -sS --http3-only -k -X POST -H Host: localhost -H Content-Length: 9
-H Content-Type:  --data-binary @.../curl.data.bin --connect-timeout 3 --max-time 3
https://127.0.0.1:1984/lua" generates stderr output:
curl: (28) Operation timed out after 3000 milliseconds with 187 out of 187 bytes received

Key information: curl received the full 187-byte 500 response but waited until the --max-time 3-second timeout expired before exiting.
Subsequently, the IPC::Run timer also timed out (in the CI high-load environment, it triggered before curl), directly terminating the test process and causing the subsequent 8 tests to fail, changing the plan from 52 to 44.

Same issue on curl repo:

• http3 ngtcp2: QUIC connection left intact after Operation timed out  curl/curl#12064
• http3: curl stalls when stream is closed before sending all upload data curl/curl#9122

curl fix it at 8.5.0: curl/curl@9cc5787

The current version of this repo release is 8.3.0

So I plan to make this repo release curl 8.20.0 to meet the testing requirements of the lua-nginx-module.

My release test on this PR: https://github.com/tzssangglass/openresty-deps-prebuild/releases/tag/v1.0.1

I hereby granted the copyright of the changes in this pull request
to the authors of this openresty-deps-prebuild project.

[tzssangglass]

another new CI failed: https://github.com/openresty/lua-nginx-module/actions/runs/27594856817/job/81582963875

cc @zhuizhuhaomeng

[zhuizhuhaomeng]

We can use the curl directly from https://github.com/stunnel/static-curl

[tzssangglass]

We can use the curl directly from stunnel/static-curl

ok, openresty/lua-nginx-module#2509