chore(python): avoid .nox directories when building docs (#71)

Source-Link: googleapis/synthtool@7e1f6da
Post-Processor: gcr.io/repo-automation-bots/owlbot-python:latest@sha256:a1a891041baa4ffbe1a809ac1b8b9b4a71887293c9101c88e8e255943c5aec2d

Author: gcf-owl-bot[bot]

packages/google-cloud-dns/.github/.OwlBot.lock.yaml

@@ -1,3 +1,3 @@
 docker:
   image: gcr.io/repo-automation-bots/owlbot-python:latest
-  digest: sha256:aea14a583128771ae8aefa364e1652f3c56070168ef31beb203534222d842b8b
+  digest: sha256:a1a891041baa4ffbe1a809ac1b8b9b4a71887293c9101c88e8e255943c5aec2d

packages/google-cloud-dns/docs/conf.py

@@ -110,6 +110,7 @@
 # directories to ignore when looking for source files.
 exclude_patterns = [
     "_build",
+    "**/.nox/**/*",
     "samples/AUTHORING_GUIDE.md",
     "samples/CONTRIBUTING.md",
     "samples/snippets/README.rst",