Particles example segfaults on exit on macOS

See https://github.com/gazebosim/gazebo_test_cases/issues/708

### System

- MacBook Pro 2021, Apple M1 Max, 32 GB
- macOS Ventura 13.4
- Xcode 14.3.1

### Test

ogre2 version runs but reports segmentation fault on exit

```bash
./particles_demo ogre2 metal
[Msg] Loading plugin [gz-rendering-ogre2]
[Dbg] [Ogre2ParticleEmitter.cc:504] Particle emitter initialized
[Dbg] [Ogre2ParticleEmitter.cc:504] Particle emitter initialized
[Dbg] [Ogre2ParticleEmitter.cc:504] Particle emitter initialized
[Dbg] [Ogre2ParticleEmitter.cc:504] Particle emitter initialized
[Dbg] [Ogre2ParticleEmitter.cc:504] Particle emitter initialized
===============================
TAB - Switch render engines
ESC - Exit
===============================
2023-09-14 12:12:32.993 particles_demo[77830:36450509] DEBUG Pre: Retain count is 3
2023-09-14 12:12:32.993 particles_demo[77830:36450509] DEBUG Pos: Retain count is 4
2023-09-14 12:12:32.994 particles_demo[77830:36450509] DEBUG Pos2: Retain count is 3
2023-09-14 12:12:32.994 particles_demo[77830:36450509] DEBUG Pre: Retain count is 2
2023-09-14 12:12:32.994 particles_demo[77830:36450509] DEBUG Pos: Retain count is 3
2023-09-14 12:12:32.995 particles_demo[77830:36450509] DEBUG Pos2: Retain count is 2
2023-09-14 12:12:32.995 particles_demo[77830:36450509] DEBUG Pre: Retain count is 1
2023-09-14 12:12:32.995 particles_demo[77830:36450509] DEBUG Pos: Retain count is 2
2023-09-14 12:12:32.996 particles_demo[77830:36450509] DEBUG Pos2: Retain count is 1
zsh: segmentation fault ./particles_demo ogre2 metal
rhys@MacBookPro2 build % ./particles_demo ogre2 metal
[Msg] Loading plugin [gz-rendering-ogre2]
[Dbg] [Ogre2ParticleEmitter.cc:504] Particle emitter initialized
[Dbg] [Ogre2ParticleEmitter.cc:504] Particle emitter initialized
[Dbg] [Ogre2ParticleEmitter.cc:504] Particle emitter initialized
[Dbg] [Ogre2ParticleEmitter.cc:504] Particle emitter initialized
[Dbg] [Ogre2ParticleEmitter.cc:504] Particle emitter initialized
===============================
TAB - Switch render engines
ESC - Exit
===============================
2023-09-14 12:12:46.362 particles_demo[77836:36450748] DEBUG Pre: Retain count is 3
2023-09-14 12:12:46.362 particles_demo[77836:36450748] DEBUG Pos: Retain count is 4
2023-09-14 12:12:46.362 particles_demo[77836:36450748] DEBUG Pos2: Retain count is 3
2023-09-14 12:12:46.362 particles_demo[77836:36450748] DEBUG Pre: Retain count is 2
2023-09-14 12:12:46.362 particles_demo[77836:36450748] DEBUG Pos: Retain count is 3
2023-09-14 12:12:46.363 particles_demo[77836:36450748] DEBUG Pos2: Retain count is 2
2023-09-14 12:12:46.363 particles_demo[77836:36450748] DEBUG Pre: Retain count is 1
2023-09-14 12:12:46.363 particles_demo[77836:36450748] DEBUG Pos: Retain count is 2
2023-09-14 12:12:46.364 particles_demo[77836:36450748] DEBUG Pos2: Retain count is 1
zsh: segmentation fault ./particles_demo ogre2 metal
```