doc: follow-up improvements related to change of theme

- remove breadcrumbs.html leading to building error in pydata-sphinx-theme
- added pydata-sphinx-theme in all requirements and removed unused sphinx-rtd-theme.

Author: mrava87

docs/source/_templates/breadcrumbs.html

@@ -30,7 +30,7 @@ dependencies:
     - spgl1
     - pytest-runner
     - setuptools_scm
-    - sphinx-rtd-theme
+    - pydata-sphinx-theme
     - sphinx-gallery
     - nbsphinx
     - image

environment-dev.yml

@@ -9,6 +9,6 @@ build:
 
 python:
   install:
-    - requirements: requirements-doc.txt
+    - requirements: requirements-dev.txt
     - method: setuptools
       path: .

readthedocs.yml

@@ -15,7 +15,7 @@ pytest-runner
 setuptools_scm
 docutils<0.18
 Sphinx
-sphinx-rtd-theme
+pydata-sphinx-theme
 sphinx-gallery
 numpydoc
 nbsphinx