Implement automatic version metadata sync

This version value has historically been manually updated, but modern
python versions include a version library to read the version of the
library you are currently running, so the library itself can read its
own package version and provide it to users here.

Primary difference here is instead of manual version in tuple with
auto-string generation, now we use the package string then auto-generate
the tuple-of-integers version from the string version.

Fixes #47

ib_async/version.py

@@ -1,4 +1,10 @@
 """Version info."""
 
-__version_info__ = (1, 0, 0)
-__version__ = ".".join(str(v) for v in __version_info__)
+from importlib.metadata import version
+
+__version__ = version("ib_async")
+
+# historically, ib_insync has provided __version_info__ as a 3-tuple of integers,
+# so we shouldn't use non-integer version components like "1.3b1" etc or else
+# anybody consuming __version_info__ may receive values outside of ranges they expect.
+__version_info__ = tuple([int(x) for x in __version__.split(".")])