[examples] better PL version check (#8429)

examples/lightning_base.py

@@ -4,6 +4,7 @@ import os
 from pathlib import Path
 from typing import Any, Dict
 
+import packaging
 import pytorch_lightning as pl
 from pytorch_lightning.utilities import rank_zero_info
 
@@ -33,16 +34,18 @@ from transformers.optimization import (
 
 logger = logging.getLogger(__name__)
 
-try:
-    pkg = "pytorch_lightning"
-    min_ver = "1.0.4"
-    pkg_resources.require(f"{pkg}>={min_ver}")
-except pkg_resources.VersionConflict:
+
+def require_min_ver(pkg, min_ver):
+    got_ver = pkg_resources.get_distribution(pkg).version
+    if packaging.version.parse(got_ver) < packaging.version.parse(min_ver):
         logger.warning(
-        f"{pkg}>={min_ver} is required for a normal functioning of this module, but found {pkg}=={pkg_resources.get_distribution(pkg).version}. Try pip install -r examples/requirements.txt"
+            f"{pkg}>={min_ver} is required for a normal functioning of this module, but found {pkg}=={got_ver}. "
+            "Try: pip install -r examples/requirements.txt"
         )
 
 
+require_min_ver("pytorch_lightning", "1.0.4")
+
 MODEL_MODES = {
     "base": AutoModel,
     "sequence-classification": AutoModelForSequenceClassification,