update readthedocs config

- remove docs/environment.yml
- install nodejs with RTD build.tools

Author: minrk

docs/environment.yml

@@ -1,18 +1,16 @@
 version: 2
 
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.10"
+    nodejs: "18"
+
 sphinx:
   configuration: docs/source/conf.py
 
-conda:
-  environment: docs/environment.yml
-
-build:
-  image: latest
-
 python:
-  version: 3.8
   install:
     # install ipp itself
-    - method: pip
-      path: .
+    - path: .
     - requirements: docs/requirements.txt