fix: gate asyncio import during init; disable it in cleanup CI to avoid early ssl load

PythonQt::init() unconditionally imported `asyncio`. On Python 3.12 this
pulls in `asyncio.sslproto` -> `ssl` -> the `_ssl` C extension. In our
"cleanup" test on Ubuntu 24.04 (with sanitizers and rapid finalize),
that early `_ssl` load segfaulted inside import/teardown.

Author: jcfr

.github/workflows/build.yml

@@ -88,6 +88,7 @@ jobs:
         PYTHONDEVMODE=1 PYTHONASYNCIODEBUG=1 PYTHONWARNINGS=error PYTHONMALLOC=malloc_debug \
         UBSAN_OPTIONS="halt_on_error=1" ASAN_OPTIONS="detect_leaks=1:detect_stack_use_after_return=1:fast_unwind_on_malloc=0" \
         PYTHONQT_RUN_ONLY_CLEANUP_TESTS=1 \
+        PYTHONQT_DISABLE_ASYNCIO=1 \
           make check TESTARGS="-platform minimal"
       
     - name: Generate Wrappers

src/PythonQt.cpp

@@ -102,12 +102,17 @@ void PythonQt::init(int flags, const QByteArray& pythonQtModuleName)
     }
 
 #ifdef PY3K
-    PythonQtObjectPtr asyncio;
-    asyncio.setNewRef(PyImport_ImportModule("asyncio"));
-    if (asyncio)
-    {
-      _self->_p->_pyEnsureFuture = asyncio.getVariable("ensure_future");
-      _self->_p->_pyFutureClass = asyncio.getVariable("Future");
+    // Import asyncio only when not explicitly disabled.
+    // Importing asyncio on Py3.12+ pulls in ssl/_ssl; some environments/tests
+    // want to avoid that during early embedded init.
+    if (!qEnvironmentVariableIsSet("PYTHONQT_DISABLE_ASYNCIO")) {
+        PythonQtObjectPtr asyncio;
+        asyncio.setNewRef(PyImport_ImportModule("asyncio"));
+        if (asyncio)
+        {
+          _self->_p->_pyEnsureFuture = asyncio.getVariable("ensure_future");
+          _self->_p->_pyFutureClass = asyncio.getVariable("Future");
+        }
     }
 #endif