chore: exclude .nox from linting; update python versions in CONTRIB…

…UTING (#52)

* changes without context

        autosynth cannot find the source of changes triggered by earlier changes in this
        repository, or by version upgrades to tools such as linters.

* chore(deps): update precommit hook pre-commit/pre-commit-hooks to v3.4.0

Co-authored-by: Tres Seaver <tseaver@palladion.com>

Source-Author: WhiteSource Renovate <bot@renovateapp.com>
Source-Date: Wed Dec 16 18:13:24 2020 +0100
Source-Repo: googleapis/synthtool
Source-Sha: aa255b15d52b6d8950cca48cfdf58f7d27a60c8a
Source-Link: googleapis/synthtool@aa255b1

* docs(python): document adding Python 3.9 support, dropping 3.5 support

Closes #787

Source-Author: Tres Seaver <tseaver@palladion.com>
Source-Date: Thu Dec 17 16:08:02 2020 -0500
Source-Repo: googleapis/synthtool
Source-Sha: b670a77a454f415d247907908e8ee7943e06d718
Source-Link: googleapis/synthtool@b670a77

* chore: exclude `.nox` directories from linting

The samples tests create `.nox` directories
with all dependencies installed. These directories
should be excluded from linting.

I've tested this change locally, and it significantly
speeds up linting on my machine.

Source-Author: Tim Swast <swast@google.com>
Source-Date: Tue Dec 22 13:04:04 2020 -0600
Source-Repo: googleapis/synthtool
Source-Sha: 373861061648b5fe5e0ac4f8a38b32d639ee93e4
Source-Link: googleapis/synthtool@3738610

Co-authored-by: Bu Sun Kim <8822365+busunkim96@users.noreply.github.com>

packages/google-cloud-scheduler/.flake8

@@ -26,6 +26,7 @@ exclude =
   *_pb2.py
 
   # Standard linting exemptions.
+  **/.nox/**
   __pycache__,
   .git,
   *.pyc,

packages/google-cloud-scheduler/CONTRIBUTING.rst

@@ -21,8 +21,8 @@ In order to add a feature:
 - The feature must be documented in both the API and narrative
   documentation.
 
-- The feature must work fully on the following CPython versions:  2.7,
-  3.5, 3.6, 3.7 and 3.8 on both UNIX and Windows.
+- The feature must work fully on the following CPython versions:
+  3.6, 3.7, 3.8 and 3.9 on both UNIX and Windows.
 
 - The feature must not add unnecessary dependencies (where
   "unnecessary" is of course subjective, but new dependencies should
@@ -202,25 +202,24 @@ Supported Python Versions
 
 We support:
 
--  `Python 3.5`_
 -  `Python 3.6`_
 -  `Python 3.7`_
 -  `Python 3.8`_
+-  `Python 3.9`_
 
-.. _Python 3.5: https://docs.python.org/3.5/
 .. _Python 3.6: https://docs.python.org/3.6/
 .. _Python 3.7: https://docs.python.org/3.7/
 .. _Python 3.8: https://docs.python.org/3.8/
+.. _Python 3.9: https://docs.python.org/3.9/
 
 
 Supported versions can be found in our ``noxfile.py`` `config`_.
 
 .. _config: https://github.com/googleapis/python-scheduler/blob/master/noxfile.py
 
-Python 2.7 support is deprecated. All code changes should maintain Python 2.7 compatibility until January 1, 2020.
 
 We also explicitly decided to support Python 3 beginning with version
-3.5. Reasons for this include:
+3.6. Reasons for this include:
 
 -  Encouraging use of newest versions of Python 3
 -  Taking the lead of `prominent`_ open-source `projects`_

packages/google-cloud-scheduler/synth.metadata

@@ -19,14 +19,14 @@
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "18c5dbdb4ac8cf75d4d8174e7b4558f48e76f8a1"
+        "sha": "373861061648b5fe5e0ac4f8a38b32d639ee93e4"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "18c5dbdb4ac8cf75d4d8174e7b4558f48e76f8a1"
+        "sha": "373861061648b5fe5e0ac4f8a38b32d639ee93e4"
       }
     }
   ],