In `get_connection`, opt for if/else over superfluous try/except block

[d-w-moore]

Here,

python-irodsclient/irods/pool.py

Line 85 in d3cbda0

try:

, we depend on a KeyError being raised from the pop operation on the idle pool, to branch into an alternative approach of forging a new connection.

If however KeyError were raised from other sources, due either to unforeseen problems with the code as-is or future developments of the Pool.get_connection method, this approach could go sideways, resulting in the new connection code being executed for potentially the wrong reasons.

if/else is more direct and less likely to fail.

See this PR to view the code changes being spoken of here.