Avoid deprecated license specification format

Fix this pip warning:

	********************************************************************************
	Please use a simple string containing a SPDX expression for `project.license`. You can also use `project.license-files`. (Both options available on setuptools>=77.0.0).

	By 2026-Feb-18, you need to update your project and remove deprecated calls
	or your builds will no longer be supported.

	See https://packaging.python.org/en/latest/guides/writing-pyproject-toml/#license for details.
	********************************************************************************

Author: DimitriPapadopoulos

.github/workflows/tests.yml

@@ -20,7 +20,6 @@ jobs:
       fail-fast: false
       matrix:
         python-version:
-          - "3.8"
           - "3.9"
           - "3.10"
           - "3.11"

README.rst

@@ -20,7 +20,7 @@ Useful links
 Requirements
 ------------
 
-Python 3.8 or above.
+Python 3.9 or above.
 
 Installation
 ------------

pyproject.toml

@@ -4,8 +4,8 @@
 name = "codespell"
 description = "Fix common misspellings in text files"
 readme = { file = "README.rst", content-type = "text/x-rst" }
-requires-python = ">=3.8"
-license = {text = "GPL-2.0-only"}
+requires-python = ">=3.9"
+license = "GPL-2.0-only"
 authors = [
     {name = "Lucas De Marchi", email = "[email protected]"},
 ]
@@ -21,7 +21,6 @@ classifiers = [
     "Programming Language :: Python",
     "Programming Language :: Python :: 3",
     "Programming Language :: Python :: 3 :: Only",
-    "Programming Language :: Python :: 3.8",
     "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
@@ -67,7 +66,7 @@ repository = "https://github.com/codespell-project/codespell"
 
 [build-system]
 build-backend = "setuptools.build_meta"
-requires = ["setuptools>=64", "setuptools_scm[toml]>=6.2, != 8.0.0"]
+requires = ["setuptools>=77", "setuptools_scm[toml]>=6.2, != 8.0.0"]
 
 [tool.setuptools_scm]
 write_to = "codespell_lib/_version.py"