Reimplementation of PR #512 with latest main branch (#520)

* changed exact pins for minimum versions

* force python<3.10

* apply same changes as PR 512

.readthedocs.yml

@@ -1,11 +1,15 @@
 version: 2
+build:
+  os: ubuntu-20.04
+  tools:
+    python: mambaforge-4.10
 sphinx:
   configuration: docs/conf.py
-formats:
-  - pdf
-conda:
-  environment: environment.yml
 python:
   install:
-    - method: pip
-      path: .
+  - method: pip
+    path: .
+conda:
+  environment: environment.yml
+formats:
+- pdf