chore(python): include py.typed files in release (#145)

A py.typed file must be included in the released package for it to be considered typed by type checkers. https://www.python.org/dev/peps/pep-0561/#packaging-type-information. See https://github.com/googleapis/python-secret-manager/issues/79

Source-Author: Bu Sun Kim <8822365+busunkim96@users.noreply.github.com>
Source-Date: Fri Feb 5 17:32:06 2021 -0700
Source-Repo: googleapis/synthtool
Source-Sha: 33366574ffb9e11737b3547eb6f020ecae0536e8
Source-Link: https://github.com/googleapis/synthtool/commit/33366574ffb9e11737b3547eb6f020ecae0536e8
diff --git a/synth.metadata b/synth.metadata
index f4b30cf..fec849e 100644
--- a/synth.metadata
+++ b/synth.metadata
@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/python-api-core.git",
-        "sha": "786e9de706be03354d08ad98d1988eafb0628313"
+        "sha": "94c76e0873e5b2f42331d5b1ad286c1e63b61395"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "d1bb9173100f62c0cfc8f3138b62241e7f47ca6a"
+        "sha": "33366574ffb9e11737b3547eb6f020ecae0536e8"
       }
     }
   ],