Add Apache-2.0 license metadata to pyproject.toml (#19)

Include both the license field and classifier to ensure proper license
metadata is exposed to downstream consumers. This addresses the missing
license information that requires exceptions in dependency scanning tools.

Author: dimitribrooks

pyproject.toml

@@ -3,11 +3,13 @@
 name = "common-expression-language"
 description = "Python bindings for the Common Expression Language (CEL)"
 readme = "README.md"
+license = "Apache-2.0"
 authors = [
     {name = "Brian Thorne", email = "brian@hardbyte.nz"}
 ]
 requires-python = ">=3.11"
 classifiers = [
+    "License :: OSI Approved :: Apache Software License",
     "Programming Language :: Rust",
     "Programming Language :: Python :: Implementation :: CPython",
     "Programming Language :: Python :: Implementation :: PyPy",