Drop old Sphinx version constraint to pick up global constraint

x-ref
inducer/ci-support@112ab59

Author: inducer

.github/workflows/ci.yml

@@ -108,7 +108,6 @@ jobs:
                 build_py_project_in_conda_env
                 conda install graphviz
 
-                CI_SUPPORT_SPHINX_VERSION_SPECIFIER=">=4.0"
                 build_docs
 
     downstream_tests:

.gitlab-ci.yml

@@ -82,7 +82,6 @@ Python 3 Conda:
 Documentation:
   script: |
     curl -L -O https://gitlab.tiker.net/inducer/ci-support/raw/main/build-docs.sh
-    CI_SUPPORT_SPHINX_VERSION_SPECIFIER=">=4.0"
     . ./build-docs.sh
   tags:
   - python3