samples: work-philosophers: Add target restriction

Add target restrictions to this sample as well.  Without these, nightly
runs on zephyr's main try to build for unsupported targets.

Signed-off-by: David Brown <[email protected]>

Author: d3zd3z

samples/work-philosophers/sample.yaml

@@ -9,7 +9,15 @@ common:
       - "All threads done"
   tags: rust
   filter: CONFIG_RUST_SUPPORTED
+  platform_allow:
+    - qemu_cortex_m0
+    - qemu_cortex_m3
+    - qemu_riscv32
+    - qemu_riscv32/qemu_virt_riscv32/smp
+    - qemu_riscv64
+    - qemu_riscv64/qemu_virt_riscv64/smp
+    - nrf52840dk/nrf52840
 tests:
-  sample.rust.philosopher:
+  sample.rust.work-philosopher:
     tags: introduction
     min_ram: 32