Install trio in RTD and use importlib.metadata.version

Author: A5rocks

.readthedocs.yml

@@ -13,6 +13,7 @@ build:
 python:
   install:
     - requirements: docs-requirements.txt
+    - path: .
 
 sphinx:
   fail_on_warning: true

docs/source/conf.py

@@ -315,9 +315,9 @@ def add_mapping(
 # built documents.
 #
 # The short X.Y version.
-import trio
+import importlib.metadata
 
-version = trio.__version__
+version = importlib.metadata.version("trio")
 # The full version, including alpha/beta/rc tags.
 release = version