pin transitive dep ciscoconfparser to fix hanging tests

Pack tests have been hanging in both GHA and CircleCI for some time.

The last good weekly tests had ciscoconfparse 1.5.46:
https://app.circleci.com/pipelines/github/StackStorm-Exchange/stackstorm-napalm/112/workflows/8acf5638-a6ee-4b15-80cd-b75e65dd2bd2/jobs/487

The first failed weekly test had ciscoconfparse 1.5.49:
https://app.circleci.com/pipelines/github/StackStorm-Exchange/stackstorm-napalm/113/workflows/59993c12-7eb3-493d-885d-e24ff00ff25f/jobs/488

1.5.48 also hangs pack tests. I tested that here:
https://github.com/StackStorm-Exchange/stackstorm-napalm/runs/4620513405

So, we pin ciscoconfparse to <1.5.48.

Author: cognifloyd

requirements.txt

@@ -1,4 +1,6 @@
-# Invalidate CircleCI cache: v2
 napalm<3.0
 json2table
 GitPython
+# transitive deps: (napalm deps)
+#   pack tests hang with ciscoconfparse 1.5.48+
+ciscoconfparse<1.5.48