samples: philosophers: Disable networking

When networking is selected, building the test
fails with:
error: static assertion failed: "Too many traffic classes"

Signed-off-by: Mateusz Holenko <mholenko@antmicro.com>
diff --git a/samples/philosophers/sample.yaml b/samples/philosophers/sample.yaml
index c22178c..75ec242 100644
--- a/samples/philosophers/sample.yaml
+++ b/samples/philosophers/sample.yaml
@@ -36,6 +36,7 @@
       - CONFIG_NUM_PREEMPT_PRIORITIES=6
       - CONFIG_NUM_COOP_PRIORITIES=0
       - CONFIG_BT=n
+      - CONFIG_NETWORKING=n
   sample.kernel.philosopher.coop_only:
     extra_configs:
       - CONFIG_NUM_PREEMPT_PRIORITIES=0