attempt to fix memory error during creation of doc env (#121)

Author: Joe Hamman

.readthedocs.yml

@@ -5,6 +5,11 @@
 # Required
 version: 2
 
+build:
+  os: "ubuntu-20.04"
+  tools:
+    python: "mambaforge-4.10"
+
 # Build documentation in the docs/ directory with Sphinx
 sphinx:
   configuration: docs/source/conf.py

ci/environment-docs.yml

@@ -1,8 +1,9 @@
 name: intake-stac
 channels:
   - conda-forge
+  - nodefaults
 dependencies:
-  - python=3.7
+  - python=3.9
   - aiohttp
   - fsspec
   - geopandas