Cannot run kunit tests

**Describe the bug**

Currentlly, it is not possible to run [Kunit](https://www.kernel.org/doc/html/latest/dev-tools/kunit/index.html) tests while doing kernel development inside toolbox.

This seems to be related to `/dev/shm`. Here is the output when trying to run the compiled `um` architecture kernel:

```
❯ ./.kunit/linux
Core dump limits :
soft - NONE
hard - NONE
Checking that ptrace can change system call numbers...OK
Checking syscall emulation for ptrace...OK
Checking environment variables for a tempdir...none found
Checking if /dev/shm is on tmpfs...OK
Checking PROT_EXEC mmap in /dev/shm...Operation not permitted
/dev/shm must be not mounted noexec
```

**Steps how to reproduce the behaviour**
1. Clone Linux kernel `https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git`
2. Build kunit tests:
```
./tools/testing/kunit/kunit.py config
./tools/testing/kunit/kunit.py exec
```
3. Execute kernel executable:
```
./.kunit/linux
```

I am running the executable directly since that will show the error properly. Using `kunit.py run` will just show unhelpful error that KTAP output was missing.

**Output of `toolbox --version` (v0.0.90+)**
e.g., `toolbox version 0.0.90`

**Toolbx package info (`rpm -q toolbox`)**

toolbox version 0.0.99.6

**Output of `podman version`**
e.g.,
```
Client: Podman Engine
Version: 5.2.3
API Version: 5.2.3
Go Version: go1.22.7
Built: Tue Sep 24 05:30:00 2024
OS/Arch: linux/amd64
```

**Podman package info (`rpm -q podman`)**

`podman-5.2.3-1.fc40.x86_64`

**Info about your OS**

Fedora Sway Atomic 40