Update pytorch-lightning requirement from <2.0.0,>1.7.0 to >1.7.0,<2.1.0 in /requirements

requirements/base.txt

@@ -1,5 +1,5 @@
 numpy <1.25.0
-pytorch-lightning >1.7.0, <2.0.0  # strict
+pytorch-lightning >1.7.0, <2.1.0
 torchmetrics <0.11.0  # strict
 lightning-utilities >0.3.1  # this is needed for PL 1.7
 torchvision >=0.10.0  # todo: move to topic related extras

src/pl_bolts/callbacks/data_monitor.py

@@ -2,10 +2,11 @@
 
 import numpy as np
 import torch
+from lightning_utilities import apply_to_collection
 from pytorch_lightning import Callback, LightningModule, Trainer
 from pytorch_lightning.loggers import TensorBoardLogger, WandbLogger
 from pytorch_lightning.utilities import rank_zero_warn
-from pytorch_lightning.utilities.apply_func import apply_to_collection
+
 from torch import Tensor, nn
 from torch.nn import Module
 from torch.utils.hooks import RemovableHandle

src/pl_bolts/callbacks/verification/batch_gradient.py

@@ -4,8 +4,8 @@
 
 import torch
 import torch.nn as nn
+from lightning_utilities import apply_to_collection
 from pytorch_lightning import LightningModule, Trainer
-from pytorch_lightning.utilities.apply_func import apply_to_collection
 from pytorch_lightning.utilities.exceptions import MisconfigurationException
 from torch import Tensor