Enable build with older versions of py-setuptools.

--- pyproject.toml.orig	2025-12-10 11:50:47 UTC
+++ pyproject.toml
@@ -12,7 +12,7 @@ readme = "README.md"
 name = "django-treebeard"
 description = "Efficient tree implementations for Django"
 readme = "README.md"
-license = "Apache-2.0"
+license = { text="Apache-2.0" }
 requires-python = ">=3.10"
 dynamic = ["version"]
 classifiers = [
@@ -53,4 +53,4 @@ lint.select = [
     "I",    # isort
     "F",    # pyflakes
     "E",    # pycodestyle errors
-]
\ No newline at end of file
+]