Bump kazoo version to 2.6.0 that supports SSL.

Allow to configure ssl config options via conf
* keyfile
* keyfile_password
* certfile
* use_ssl
* verify_certs

https://kazoo.readthedocs.io/en/latest/api/client.html#kazoo.client.KazooClient

This should be done in conformance with Redis
jobboard backend, that already allows SSL settings.

Change-Id: Ic2670c3c4caa93f69bc2d541c3701df2b6037d2e

The networkx 2.x series has been out for two years now and supports
python 3.6 and greater[1]. This patch updates TaskFlow to require
a minimum of networkx 2.1. It also updates the code to support
recent deprecation expiration introduced in the 2.4 release.

[1] https://networkx.github.io/documentation/stable/news.html

Change-Id: Ife31d353ba80824ebc63c8b21ee90943badc8da3

The "digestmod" parameter must be passed in for Python 3.8.

md5 was chosen here because this is what was implicitly used
for Python < 3.8.

Change-Id: I17eca0692c4a89ff90cfa9d4ef3947d2c9ee23e7

With a lot of possible retries using mysql sa.Text for result field
atomdetails table is not enough.

Updated 'results' column type to LONGTEXT in mysql backend case.

PosgreSQL seems not to be affected as postgres text type is not
having length limitation.

Co-Authored-By: Michael Johnson <johnsomor@gmail.com>

Change-Id: I4e44e3288ae49d85c5b5ce8ff26ba83f3b9d2c7b
Closes-bug: #1838015

The use of ABC classes directly from collections has been deprecated in
3.x versions of Python. The direction is to use the classes defined in
collections.abc. Python 2.7 does not have this, but Python 3.8 will be
dropping the backwards compatibility to use the old location.

Six also does not have support for this yet, so in the mean time to make
sure we don't run into issues as folks try to move to 3.8, and to get
rid of deprecation warnings in logs, this handles importing from the
preferred location and falls back if it not available.

Change-Id: I15554bf3c109045ebdc237ce7cb40299f5d1b298
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>

Change-Id: Ia9964fd613efc49479e763b6a7095d63115179ab

KazooClient should use the taskflow logger and not the default one.
Using the default logger means that the user cannot control its
log level

Change-Id: Id9549028522955ece0ae9f675c5ecc1c2fd816de
Closes-Bug: #1785036

Avoid redirects, s/http/https/.

Change-Id: Id03bd49f250b48109967a0e04b92b75925f08932

With the release of NetworkX 2.0 the reporting API was
moved to view/iterator model. Many methods were moved from
reporting lists or dicts to iterating over the information.
Methods that used to return containers now return views and
methods that returned iterators have been removed in networkx.
Because of this change in NetworkX 2.0 , taskflow code
have to be changed also to support networkx > 2.0

Change-Id: I23c226f37bd85c1e38039fbcb302a2d0de49f333
Closes-Bug: #1778115