Relax sphinx constraint

Newest version of myst-parser (required for latest sphinx)
doesn't support python 3.9

Author: xylar

pyproject.toml

@@ -31,7 +31,7 @@ dependencies = [
 [project.optional-dependencies]
 docs = [
     # building documentation
-    "sphinx >=8.0.0",
+    "sphinx >=7.0.0",
     "sphinx_rtd_theme",
     "myst-parser",
     "sphinx-multiversion",

spec-file.txt

@@ -19,7 +19,7 @@ mypy
 pre-commit
 
 # Documentation
-sphinx >=8.0.0
+sphinx >=7.0.0
 sphinx_rtd_theme
 myst-parser
 sphinx-multiversion