Replace requirements.txt with extra dependency doc

Author: honno

.github/workflows/pages.yml

@@ -76,8 +76,7 @@ jobs:
       # Install dependencies:
       - name: 'Install dependencies'
         run: |
-          pip install -r ./requirements.txt
-          pip install .
+          pip install .[doc]
 
       # Generate the documentation:
       - name: 'Build documentation'

pyproject.toml

@@ -14,6 +14,17 @@ Source = "https://github.com/data-apis/array-api/"
 Documentation = "https://data-apis.org/array-api/"
 Homepage = "https://data-apis.org/"
 
+[project.optional-dependencies]
+doc = [
+    "sphinx==4.3.0",
+    "sphinx-material==0.0.30",
+    "myst-parser",
+    "sphinx_markdown_tables",
+    "sphinx_copybutton",
+    "docutils<0.18",
+    "sphinx-math-dollar",
+]
+
 [build-system]
 requires = ["setuptools"]
 build-backend = "setuptools.build_meta"