fix PIL.LINEAR warning

Summary:
Fix these warnings:

```
/data/sandcastle/boxes/fbsource/buck-out/v2/gen/fbcode/f151e79da24bacb4/surreal/efm/__manual_train__/manual_train#link-tree/detectron2/data/transforms/transform.py:46: DeprecationWarning: LINEAR is deprecated and will be removed in Pillow 10 (2023-07-01). Use BILINEAR or Resampling.BILINEAR instead.
  def __init__(self, src_rect, output_size, interp=Image.LINEAR, fill=0):
/data/sandcastle/boxes/fbsource/buck-out/v2/gen/fbcode/f151e79da24bacb4/surreal/efm/__manual_train__/manual_train#link-tree/detectron2/data/transforms/transform.py:46: DeprecationWarning: LINEAR is deprecated and will be removed in Pillow 10 (2023-07-01). Use BILINEAR or Resampling.BILINEAR instead.
  def __init__(self, src_rect, output_size, interp=Image.LINEAR, fill=0):
/data/sandcastle/boxes/fbsource/buck-out/v2/gen/fbcode/f151e79da24bacb4/surreal/efm/__manual_train__/manual_train#link-tree/detectron2/data/transforms/transform.py:46: DeprecationWarning: LINEAR is deprecated and will be removed in Pillow 10 (2023-07-01). Use BILINEAR or Resampling.BILINEAR instead.
  def __init__(self, src_rect, output_size, interp=Image.LINEAR, fill=0):
/data/sandcastle/boxes/fbsource/buck-out/v2/gen/fbcode/f151e79da24bacb4/surreal/efm/__manual_train__/manual_train#link-tree/detectron2/data/transforms/transform.py:46: DeprecationWarning: LINEAR is deprecated and will be removed in Pillow 10 (2023-07-01). Use BILINEAR or Resampling.BILINEAR instead.
  def __init__(self, src_rect, output_size, interp=Image.LINEAR, fill=0):
```

Reviewed By: hlzz

Differential Revision: D47212305

fbshipit-source-id: 8944e8fdbf9e3669df8d5d8350073f2af7108af1

Author: ddetone

detectron2/data/transforms/transform.py

@@ -43,7 +43,7 @@ class ExtentTransform(Transform):
     See: https://pillow.readthedocs.io/en/latest/PIL.html#PIL.ImageTransform.ExtentTransform
     """
 
-    def __init__(self, src_rect, output_size, interp=Image.LINEAR, fill=0):
+    def __init__(self, src_rect, output_size, interp=Image.BILINEAR, fill=0):
         """
         Args:
             src_rect (x0, y0, x1, y1): src coordinates