Drop support for Sphinx 4 (#124)

Author: sciencewhiz

.github/workflows/workflow.yml

@@ -69,7 +69,7 @@ jobs:
       fail-fast: false
       matrix:
         python-version: ['pypy3.9', '3.8', '3.9', '3.10', '3.11', '3.12']
-        sphinx-version: ['>=4,<5', '>=5,<6', '>=6a0,<7', '>=7,<8']
+        sphinx-version: ['>=5,<6', '>=6a0,<7', '>=7,<8']
         os: [windows-latest, macos-latest, ubuntu-latest]
     steps:
       - uses: actions/checkout@v4

setup.py

@@ -14,7 +14,7 @@
     long_description_content_type="text/markdown",
     url="https://github.com/wpilibsuite/sphinxext-opengraph",
     license="LICENSE.md",
-    install_requires=["sphinx>=4.0"],
+    install_requires=["sphinx>=5.0"],
     packages=["sphinxext/opengraph"],
     include_package_data=True,
     package_data={"sphinxext.opengraph": ["sphinxext/opengraph/_static/*"]},