docs: add .readthedocs.yaml to migrate to RTD v2

Closes reanahub/reana#710.

.readthedocs.yaml

@@ -0,0 +1,22 @@
+# .readthedocs.yaml
+# Read the Docs configuration file
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+# Required
+version: 2
+
+# Set the version of Python
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.8"
+
+# Build documentation in the docs/ directory with Sphinx
+sphinx:
+  configuration: docs/conf.py
+
+# It is recommended to specify the dependencies to enable reproducible builds:
+# https://docs.readthedocs.io/en/stable/guides/reproducible-builds.html
+python:
+  install:
+    - requirements: docs/requirements.txt

MANIFEST.in

@@ -25,3 +25,4 @@ recursive-include docs *.rst
 recursive-include tests *.py
 recursive-include tests *.txt
 global-exclude *.py[co] .DS_Store
+exclude .readthedocs.yaml