chore: preserve 'pytype' artifacts during synth (#90)

* chore: use '.pytype' vs. 'pytype_output' for pytype cache

* chore: add snippet-bot to CI (via synth)

* chore: drop obsolete warning about editable installs

* chore: add secrets manager, docs-presubmit to CI (via synth)

* chore: manual synth

Closes: #66.
Closes: #56.
diff --git a/setup.cfg b/setup.cfg
index 5c32e16..0be0b3f 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -7,6 +7,6 @@
     google/
 exclude =
     tests/
-output = pytype_output/
+output = .pytype/
 # Workaround for https://github.com/google/pytype/issues/150
 disable = pyi-error