Release GIL when calling mkl_lapack::orgqr (#2850)

This PR fixes a deadlock in QR decomposition tests by adding GIL release
before `mkl_lapack::orgqr` call.

The hang occurred because:
1. dpnp/dpctl submits a `host_task` to manage Python object lifetimes
2. host_task needs to acquire the GIL to decrement reference counts
3. if the main thread holds the GIL during queue submission → deadlock
4. `orgqr` is currently implemented in oneMKL as GPU-to-Host reverse
offload:
```cpp
exec_q.submit([&](sycl::handler& cgh) {
  cgh.depends_on(depends);
   cgh.host_task([=]() { orgqr_host(...); });
}).wait();
```

As a solution PR proposes to release GIL using before calling the OneMKL
operations. The GIL is automatically reacquired when the function
returns (RAII).

Author: antonwolfy

CHANGELOG.md

@@ -88,6 +88,7 @@ Also, that release drops support for Python 3.9, making Python 3.10 the minimum
 * Fixed test tolerance issues for float16 intermediate precision that became visible when testing against conda-forge's NumPy [#2828](https://github.com/IntelPython/dpnp/pull/2828)
 * Ensured device aware dtype handling in `dpnp.identity` and `dpnp.gradient` [#2835](https://github.com/IntelPython/dpnp/pull/2835)
 * Fixed `dpnp.tensor.round` to use device-aware output dtype for boolean input [#2851](https://github.com/IntelPython/dpnp/pull/2851)
+* Resolved a deadlock in `dpnp.linalg.qr` by releasing the GIL before OneMKL `orgqr` call to prevent host tasks contention [#2850](https://github.com/IntelPython/dpnp/pull/2850)
 
 ### Security
 

dpnp/backend/extensions/lapack/orgqr.cpp

@@ -87,8 +87,17 @@ static sycl::event orgqr_impl(sycl::queue &exec_q,
 
     sycl::event orgqr_event;
     try {
+        // Release GIL to avoid serialization of host task submissions
+        // to the same queue in OneMKL
+        py::gil_scoped_release lock{};
+
         scratchpad = sycl::malloc_device<T>(scratchpad_size, exec_q);
 
+        // mkl_lapack::orgqr() is done through GPU-to-Host reverse offload:
+        // exec_q.submit([&](sycl::handler& cgh) {
+        //   cgh.depends_on(depends);
+        //   cgh.host_task([=]() { orgqr_host(...); });
+        // }).wait();
         orgqr_event = mkl_lapack::orgqr(
             exec_q,
             m,          // The number of rows in the matrix; (0 ≤ m).