setup: Enable installation on Python 3.12.

Author: neiljp

setup.py

@@ -68,6 +68,7 @@ def long_description():
         "Programming Language :: Python :: 3.9",
         "Programming Language :: Python :: 3.10",
         "Programming Language :: Python :: 3.11",
+        "Programming Language :: Python :: 3.12",
         "Programming Language :: Python :: Implementation :: CPython",
         "Programming Language :: Python :: Implementation :: PyPy",
     ],
@@ -77,7 +78,7 @@ def long_description():
         "Issues": "https://github.com/zulip/zulip-terminal/issues",
         "Hot Keys": "https://github.com/zulip/zulip-terminal/blob/main/docs/hotkeys.md",
     },
-    python_requires=">=3.7, <3.12",
+    python_requires=">=3.7, <3.13",
     keywords="",
     packages=find_packages(exclude=["tests", "tests.*"]),
     zip_safe=True,