[skyrl-train] Make libnuma optional for training (#601)

# What does this PR do?

Makes `libnuma` optional for training

Signed-off-by: SumanthRH <sumanthrh99@gmail.com>

Author: SumanthRH

skyrl-train/skyrl_train/workers/worker.py

@@ -155,7 +155,13 @@ class bitmask_t(Structure):
                 ("maskp", POINTER(c_ulong)),
             ]
 
-        LIBNUMA = CDLL(find_library("numa"))
+        try:
+            LIBNUMA = CDLL(find_library("numa"))
+        except Exception as e:
+            logger.error(f"Skipping NUMA affinity setup because libnuma is not installed: {e}")
+            _SET_AFFINITY = True
+            return
+
         LIBNUMA.numa_parse_nodestring.argtypes = [c_char_p]
         LIBNUMA.numa_parse_nodestring.restype = POINTER(bitmask_t)
         LIBNUMA.numa_run_on_node_mask.argtypes = [POINTER(bitmask_t)]