Fix Read the Docs builds (#111)

* Fix Read the Docs builds

The builds have been failing for a long time
due to changes in the config file format.

This commit introduces the following changes:

* Update the Read the Docs config to meet current requirements
* De-duplicate dependencies listed in `requirements_dev.txt`
  and `environment.yml` by moving docs dependencies to
  `requirements_docs.txt` and referencing it in the RTD config
  and in the `requirements_dev.txt` file.

These changes are expected to fix RTD builds.

Author: kurtmckee

docs/environment.yml

@@ -1,8 +1,14 @@
+version: 2
+
 build:
-    image: latest
+  os: 'ubuntu-24.04'
+  tools:
+    python: '3.13'
 
-python:
-    version: 3.7
+sphinx:
+  configuration: 'docs/source/conf.py'
+  fail_on_warning: true
 
-conda:
-    file: docs/environment.yml
+python:
+  install:
+    - requirements: 'requirements_docs.txt'

readthedocs.yml

@@ -1,10 +1,6 @@
+-r requirements_docs.txt
 pytest
 flake8
-sphinx
-nbsphinx
-pandoc
-ipykernel
-nbconvert
 defusedxml
 jinja2
 requests

requirements_dev.txt

@@ -0,0 +1,5 @@
+sphinx
+nbsphinx
+pandoc
+nbconvert
+ipykernel

requirements_docs.txt

@@ -15,7 +15,13 @@
 sys.path[:0] = os.path.dirname(__file__)
 
 reqs = [line.strip() for line in open('requirements.txt')]
-dev_reqs = [line.strip() for line in open('requirements_dev.txt')]
+docs_reqs = [line.strip() for line in open('requirements_docs.txt')]
+dev_reqs = [
+    line.strip()
+    for line in open('requirements_dev.txt')
+    if line.strip() and not line.strip().startswith("-r ")
+]
+dev_reqs.extend(docs_reqs)
 
 setup(name='esgf-pyclient',
       version=__version__,