readthedocs build maintenance (#43)

* Update readthedocs build config to mambaforge-22.9

* Update sphinx & its extensions

Change to pin Sphinx version as recommended by readthedocs.
Install readthedocs extensions via pip because that's where they release
them.

Update packages and versions used in recent writing env.
Noticed that cryptography and pyOpenSSL have been dropped as
dependencies.

.readthedocs.yaml

@@ -5,7 +5,7 @@ version: 2
 build:
   os: ubuntu-20.04
   tools:
-    python: "mambaforge-4.10"
+    python: "mambaforge-22.9"
 
 conda:
   environment: environment-rtd.yaml

environment-rtd.yaml

@@ -27,5 +27,7 @@ dependencies:
   - nbsphinx
   - pip
   - python=3.12
-  - sphinx
-  - sphinx_rtd_theme=1.2
+  - sphinx=7.2.6
+
+  - pip:
+    - sphinx_rtd_theme

requirements.txt

@@ -1,86 +1,83 @@
 # Python packages and versions used in recent docs development environment
 #
 # Create/update this file with:
-#   (salishseacast-docs)$ python3 -m pip list --format=freeze >> requirements.txt
+#   (salishseacast-docs)$ python -m pip list --format=freeze >> requirements.txt
 
-alabaster==0.7.13
-asttokens==2.2.1
-attrs==22.2.0
-Babel==2.12.1
-backcall==0.2.0
-backports.functools-lru-cache==1.6.4
-beautifulsoup4==4.12.2
-bleach==6.0.0
-brotlipy==0.7.0
-certifi==2023.7.22
-cffi==1.15.1
-charset-normalizer==3.1.0
+alabaster==0.7.16
+asttokens==2.4.1
+attrs==23.2.0
+Babel==2.14.0
+beautifulsoup4==4.12.3
+bleach==6.1.0
+Brotli==1.1.0
+certifi==2024.2.2
+charset-normalizer==3.3.2
 colorama==0.4.6
-cryptography==42.0.0
 decorator==5.1.1
 defusedxml==0.7.1
-docutils==0.18.1
+docutils==0.20.1
 entrypoints==0.4
-executing==1.2.0
-fastjsonschema==2.16.3
-idna==3.4
+exceptiongroup==1.2.0
+executing==2.0.1
+fastjsonschema==2.19.1
+idna==3.6
 imagesize==1.4.1
-importlib-metadata==6.3.0
-importlib-resources==5.12.0
-ipython==8.12.0
-jedi==0.18.2
+importlib-metadata==7.0.1
+importlib-resources==6.1.1
+ipython==8.21.0
+jedi==0.19.1
 Jinja2==3.1.3
-jsonschema==4.17.3
-jupyter_client==8.1.0
-jupyter_core==5.3.0
-jupyterlab-pygments==0.2.2
-MarkupSafe==2.1.2
+jsonschema==4.21.1
+jsonschema-specifications==2023.12.1
+jupyter_client==8.6.0
+jupyter_core==5.7.1
+jupyterlab_pygments==0.3.0
+MarkupSafe==2.1.5
 matplotlib-inline==0.1.6
-mistune==2.0.5
-nbclient==0.7.3
-nbconvert==7.3.1
-nbformat==5.8.0
-nbsphinx==0.9.1
-packaging==23.0
+mistune==3.0.2
+nbclient==0.8.0
+nbconvert==7.16.0
+nbformat==5.9.2
+nbsphinx==0.9.3
+packaging==23.2
 pandocfilters==1.5.0
 parso==0.8.3
-pexpect==4.8.0
+pexpect==4.9.0
 pickleshare==0.7.5
-pip==23.3
+pip==24.0
 pkgutil_resolve_name==1.3.10
-platformdirs==3.2.0
-prompt-toolkit==3.0.38
+platformdirs==4.2.0
+prompt-toolkit==3.0.42
 ptyprocess==0.7.0
 pure-eval==0.2.2
-pycparser==2.21
-Pygments==2.15.0
-pyOpenSSL==23.1.1
-pyrsistent==0.19.3
+Pygments==2.17.2
 PySocks==1.7.1
 python-dateutil==2.8.2
-pytz==2023.3
-pyzmq==25.0.2
+pytz==2024.1
+pyzmq==25.1.2
+referencing==0.33.0
 requests==2.31.0
-setuptools==67.6.1
+rpds-py==0.17.1
+setuptools==69.0.3
 six==1.16.0
 snowballstemmer==2.2.0
-soupsieve==2.3.2.post1
-Sphinx==6.1.3
-sphinx-rtd-theme==1.2.0
-sphinxcontrib-applehelp==1.0.4
-sphinxcontrib-devhelp==1.0.2
-sphinxcontrib-htmlhelp==2.0.1
+soupsieve==2.5
+Sphinx==7.2.6
+sphinx-rtd-theme==2.0.0
+sphinxcontrib-applehelp==1.0.8
+sphinxcontrib-devhelp==1.0.6
+sphinxcontrib-htmlhelp==2.0.5
 sphinxcontrib-jquery==4.1
 sphinxcontrib-jsmath==1.0.1
-sphinxcontrib-qthelp==1.0.3
-sphinxcontrib-serializinghtml==1.1.5
+sphinxcontrib-qthelp==1.0.7
+sphinxcontrib-serializinghtml==1.1.10
 stack-data==0.6.2
 tinycss2==1.2.1
 tornado==6.3.3
-traitlets==5.9.0
-typing_extensions==4.5.0
-urllib3==1.26.18
-wcwidth==0.2.6
+traitlets==5.14.1
+typing_extensions==4.9.0
+urllib3==2.2.0
+wcwidth==0.2.13
 webencodings==0.5.1
-wheel==0.40.0
-zipp==3.15.0
+wheel==0.42.0
+zipp==3.17.0