Pin OpenSSL below 4 to fix nightly conan builds

[PengZheng]

Problem

The nightly linux-build-conan jobs started failing on 2026-08-11 with civetweb/1.16 compile errors against the OpenSSL headers:

• civetweb.c:1561: #error "Please define OPENSSL_API_#_# or USE_MBEDTLS"
• X509_get_subject_name/X509_get_issuer_name discard const (error under -pedantic-errors)
• mg_openssl_initialized undeclared

Root cause

ConanCenter published openssl/4.0.1 between 08-10 and 08-11. The unbounded openssl/[>=3.2.0] range in conanfile.py resolved to it (the override=True also drops the <4 upper bound that the civetweb recipe itself declares). civetweb/1.16 predates the OpenSSL 4 API, so its API-version detection has no branch for OpenSSL >= 4.0.

Fix

Restrict the range to openssl/[>=3.2.0 <4], matching the upper bound already declared by the civetweb recipe.

Verified locally: conan graph info now resolves openssl/3.6.3.

Follow-up

Revisit once civetweb (or another consumer) supports the OpenSSL 4 API, then the bound can be lifted again.

🤖 Generated with Claude Code

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.53%. Comparing base (d4b2ec3) to head (85f037c).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #843      +/-   ##
==========================================
- Coverage   91.62%   91.53%   -0.10%     
==========================================
  Files         235      235              
  Lines       28787    28787              
==========================================
- Hits        26377    26351      -26     
- Misses       2410     2436      +26     

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