Avoid loading pkg_resources until needed

This import took forever (0.2s) and was used only for the version
command, so don't import it except where it's needed.

client-cli/pvc/cli/cli.py

@@ -25,9 +25,8 @@ from functools import wraps
 from json import dump as jdump
 from json import dumps as jdumps
 from json import loads as jloads
-from os import environ, makedirs, path
-from pkg_resources import get_distribution
 from lxml.etree import fromstring, tostring
+from os import environ, makedirs, path
 from re import sub, match
 from yaml import load as yload
 from yaml import SafeLoader as SafeYAMLLoader
@@ -115,6 +114,8 @@ def version(ctx, param, value):
     if not value or ctx.resilient_parsing:
         return
 
+    from pkg_resources import get_distribution
+
     version = get_distribution("pvc").version
     echo(CLI_CONFIG, f"Parallel Virtual Cluster CLI client version {version}")
     ctx.exit()