Improved loop break [skip ci]

Author: ankane

lib/lightgbm/booster.rb

@@ -254,7 +254,7 @@ def load_pandas_categorical(file_name: nil, model_str: nil)
             offset = [offset, max_offset].max
             f.seek(offset, IO::SEEK_END)
             lines = f.readlines
-            if lines.length >= 2
+            if lines.length >= 2 || offset == max_offset
               break
             end
             offset *= 2