attempt to fix the install issues (#141)

* skip `sphinx=8` on `python=3.9`

(`sphinx=8` requires `python>=3.10`)

* remove the obsolete `import-metadata` install

* install `tomli` on `python<3.11`

* fetch the entire repo

Author: keewis

.github/workflows/ci.yaml

@@ -16,10 +16,17 @@ jobs:
       matrix:
         python-version: ["3.9", "3.12", "3.13"]
         sphinx-version: ["5.3", "6.2", "7.3", "7.4", "8.0", "8.1"]
+        exclude:
+          - python-version: "3.9"
+            sphinx-version: "8.0"
+          - python-version: "3.9"
+            sphinx-version: "8.1"
 
     steps:
       - name: checkout the repository
         uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
 
       - name: setup python
         uses: actions/setup-python@v5

ci/requirements.txt

@@ -1,4 +1,4 @@
-importlib-metadata; python_version < "3.8"
 packaging
 sphinx
 sphinx_rtd_theme
+tomli; python_version < "3.11"