Default NETWORK_TIMEOUT might be too low and should be configurable

[ofipify]

In the last few days we've noticed intermittent read timeouts for ops.epo.org

HTTPSConnectionPool(host='ops.epo.org', port=443): Read timed out. (read timeout=10.0)

When looking into where the timeout value is coming from, I saw that there's a constant NETWORK_TIMEOUT defined in api.py which can not be changed easily.

I will prepare a PR that will make this setting configurable when instantiating the client, defaulting to the 10 second timeout as before.

[amotl]

Hi @ofipify. Thanks a stack for your contribution GH-141. We released python-epo-ops-client 4.2.1, which includes your improvement.