Calling `sync.Server.get_node` raises an `AttributeError`.
This commit fixes the issue and adds a corresponding test.

* Resolve collections.Iterable DeprecationWarning

* Import from collections.abc

Await connection lost tasks when stopping internal server

According to OPC Unified Architecture, Part 5, 6.3.11
OperationLimitsType all Max* properties shall have datatype
UInt32.

Fix this by explicitly setting the variant type to UInt32
instead of defaulting to Int64.

This fixes connectivity issues with the KepwareServerEx OPC-UA client.

Introduced in 21432df9

Allow Asynchronous Method Calls

add conditional requirement as per https://pypi.org/project/pytest-runner/ conditional requirements instructions

* add missing publish call

* added InternalSubscription is_for_client flag

* rename is_for_client to na_acks, use isession.external prop

* docs

Fix 60 aiosqlite

* Set the correct client signature algorithm

Before, the localtime field was set to a wrong datatype (DateTime
instead of TimeZoneDataType), and didn’t contain the local timezone
offset, but the current localtime.

Previously this was hardcoded to sha1. Fix this by introducing a
new URI field in the SecurityPolicy classes carrying the correct
URIs.

This fixes complaints by some UA clients that match requested
security profiles against the server response and warn the user.

* Set the correct client signature algorithm