[FIX] core, web: Pillow 9.1 deprecations

Pillow 9.1 deprecates most if not all toplevel Image constants:
https://pillow.readthedocs.io/en/stable/releasenotes/9.1.0.html#constants

These constants have been moved to thematic enum classes (e.g. all the
resampling constants in `PIL.Image.Resampling`).

This triggers warnings in Odoo, and the removal delay is quite short
(slated for Pillow 10, release planned mid 2023). Pillow 9.1 is also
already in Debian Bookworm (current testing).

Fix by shimming at the import level: if the enums are available import
them into the local namespace, otherwise alias `PIL.Image` itself as
to the enum.

closes odoo/odoo#96799

X-original-commit: 7be04d31bad078681ef0a2919234c11840a2e8e2
Signed-off-by: Xavier Morel (xmo) <xmo@odoo.com>

addons/web/models/base_document_layout.py

@@ -1,6 +1,5 @@
 # -*- coding: utf-8 -*-
 import markupsafe
-from PIL import Image
 from markupsafe import Markup
 
 from odoo import api, fields, models, tools
@@ -14,6 +13,10 @@ except ImportError:
     # If the `sass` python library isn't found, we fallback on the
     # `sassc` executable in the path.
     libsass = None
+try:
+    from PIL.Image import Resampling
+except ImportError:
+    from PIL import Image as Resampling
 
 DEFAULT_PRIMARY = '#000000'
 DEFAULT_SECONDARY = '#000000'
@@ -204,7 +207,7 @@ class BaseDocumentLayout(models.TransientModel):
 
         # Converts to RGBA (if already RGBA, this is a noop)
         image_converted = image.convert('RGBA')
-        image_resized = image_converted.resize((w, h), resample=Image.NEAREST)
+        image_resized = image_converted.resize((w, h), resample=Resampling.NEAREST)
 
         colors = []
         for color in image_resized.getcolors(w * h):