docs: migrate .readthedocs.yml to configuration file v2 (#689)

* docs: set version: 2 in .readthedocs.yml

* move requirement file to python.requirements

* remove pip_install: true

* change build.image to build.os

* fix requirement docs name

Author: Linchin

packages/pandas-gbq/.readthedocs.yml

@@ -2,9 +2,17 @@
 # Use of this source code is governed by a BSD-style
 # license that can be found in the LICENSE file.
 
-requirements_file: docs/requirements-docs.txt
+# .readthedocs.yaml
+# Read the Docs configuration file
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+version: 2
+
 build:
-  image: latest
+  os: ubuntu-22.04
+  tools:
+    python: "3.11"
+
 python:
-  pip_install: true
-  version: 3.8
+  install:
+  - requirements: docs/requirements-docs.txt