Allow strategy in configs

Author: DomInvivo

graphium/config/_loader.py

@@ -372,7 +372,7 @@ def load_trainer(
     cfg_trainer = deepcopy(config["trainer"])
 
     # Define the IPU plugin if required
-    strategy = "auto"
+    strategy = config["trainer"]["trainer"].get("strategy", "auto")
     if accelerator_type == "ipu":
         ipu_opts, ipu_inference_opts = _get_ipu_opts(config)
 
@@ -385,6 +385,9 @@ def load_trainer(
             precision=config["trainer"]["trainer"].get("precision"),
         )
 
+        if strategy != "auto":
+            raise ValueError("IPUs selected, but strategy is not set to 'auto'")
+
         from lightning_graphcore import IPUStrategy
 
         strategy = IPUStrategy(training_opts=training_opts, inference_opts=inference_opts)