Build pybind11 3.1.0 in the scdv scripts

Both scdv scripts pinned pybind11 2.13.6, whose `eval.h` calls the
`_Py_fopen_obj` that Python 3.14 deprecates.  3.1.0 calls `Py_fopen`
from 3.14 on, so the deprecation is gone at the source rather than
merely kept quiet by the `SYSTEM` include treatment.  Ubuntu and
Windows move together so an scdv built on either ships the same
pybind11.

scipy 1.17.1 declares a pre-emptive `pybind11<3.1.0` build bound, but
its generated `requirements/build.txt` carries no upper bound and the
build is driven with `--no-build-isolation`, so the bound does not
apply and the compile is clean.

Verified on Ubuntu 24.04 with Python 3.14.5: pybind11 3.1.0 installs
into the scdv prefix through the same recipe, scipy 1.17.1 recompiles
and runs against it, and solvcon builds with `-Werror` and passes 242
gtests and 2114 pytests.

Author: yungyuc

contrib/dependency/build-scdv.sh

@@ -293,9 +293,9 @@ EOF
 
 plat_scipy_install() {
   # Runs in the unpacked scipy source directory (the caller has pushd'd).
-  # Ubuntu's pybind11-dev (2.11) at /usr/include shadows our 2.13.6 and
-  # rejects scipy's 3-arg PYBIND11_MODULE. -isystem orders our headers ahead
-  # of /usr/include so scipy compiles against the right pybind11.
+  # Ubuntu's pybind11-dev (2.11) at /usr/include shadows ours and rejects
+  # scipy's 3-arg PYBIND11_MODULE. -isystem orders our headers ahead of
+  # /usr/include so scipy compiles against the right pybind11.
   local saved_cxxflags=${CXXFLAGS:-}
   export CXXFLAGS="-isystem ${SCDV_USRDIR}/include ${saved_cxxflags}"
   with_log install.log "${PY}" -m pip install . --no-build-isolation
@@ -1277,11 +1277,11 @@ build_python() {
 
 build_pybind11() {
   scdv_skip_p pybind11 && { echo "skip: pybind11" ; return 0 ; }
-  local ver=2.13.6 full fn
+  local ver=3.1.0 full fn
   full=pybind11-${ver} ; fn=${full}.tar.gz
   download_md5 "${fn}" \
     "https://github.com/pybind/pybind11/archive/refs/tags/v${ver}.tar.gz" \
-    a04dead9c83edae6d84e2e343da7feeb
+    235664b4673257b80a9ab79f9b208e94
   unpack "${fn}" "${full}"
   mkdir -p "${SCDV_SRCDIR}/${full}/build"
   pushd "${SCDV_SRCDIR}/${full}/build" > /dev/null

contrib/dependency/windows/build-scdv-windows.ps1

@@ -917,10 +917,10 @@ function Build-Python {
 
 function Build-Pybind11 {
     if (Test-Skip 'pybind11') { Write-Host 'skip: pybind11'; return }
-    $ver = '2.13.6'; $full = "pybind11-$ver"; $fn = "$full.tar.gz"
+    $ver = '3.1.0'; $full = "pybind11-$ver"; $fn = "$full.tar.gz"
     Get-Download $fn `
         "https://github.com/pybind/pybind11/archive/refs/tags/v$ver.tar.gz" `
-        'a04dead9c83edae6d84e2e343da7feeb'
+        '235664b4673257b80a9ab79f9b208e94'
     Expand-Source $fn $full
     $bld = Join-Path $ScdvSrcDir "$full\build"
     New-Item -ItemType Directory -Force -Path $bld | Out-Null