bump min PL to 1.7 (#1596)

Author: Borda

requirements/base.txt

@@ -5,7 +5,7 @@ setuptools <=59.5.0  # Prevent install bug with tensorboard
 numpy <1.24  # strict - freeze for using np.long
 torch >1.7.0
 torchmetrics >0.7.0, <0.11.0  # strict
-pytorch-lightning >1.6.0, <1.9.0  # strict
+pytorch-lightning >1.7.0, <1.9.0  # strict
 pyDeprecate >0.1.0
 pandas >1.1.0, <=1.5.2
 jsonargparse[signatures] >4.0.0, <=4.9.0