Fix wrong version in title in Readthedocs documentation (#3815)

Co-authored-by: Bouwe Andela <b.andela@esciencecenter.nl>

.readthedocs.yaml

@@ -13,8 +13,16 @@ build:
     # DO NOT use mambaforge-*; that is currently sunsetted
     python: "miniconda-latest"
   jobs:
-    post_create_environment:
-      - conda run -n ${CONDA_DEFAULT_ENV} pip install . --no-deps
+    post_checkout:
+      # The ESMValTool repository is shallow i.e., has a .git/shallow,
+      # therefore complete the repository with a full history in order
+      # to allow setuptools-scm to correctly auto-discover the version.
+      - git fetch --unshallow
+      - git fetch --all
+    pre_install:
+      - git stash
+    post_install:
+      - git stash pop
 
 # Declare the requirements required to build your docs
 conda:
@@ -26,6 +34,11 @@ sphinx:
   configuration: doc/sphinx/source/conf.py
   fail_on_warning: true
 
+python:
+  install:
+    - method: pip
+      path: .
+
 # If using Sphinx, optionally build your docs in additional formats such as PDF
 formats:
   - pdf