Don't fail if zero results found

This was added as a protection against misconfiguration, assuming that
if zero issues were found, then there must be a typo in the config.

It's actually a legitimate scenario though - we may have a project that
for a time will have zero issues open, but on which we don't want the
tool to fail hard.

src/utils/jira.py

@@ -1,5 +1,3 @@
-import sys
-
 import dogpile.cache
 import jira
 
@@ -27,7 +25,6 @@ def query_issues(
     results = _search(jira_client, query, verbose=True)
     if not results:
         print(f"No {issue_type} found via query: {query}")
-        sys.exit(1)
     return results
 
 
@@ -50,7 +47,6 @@ def query_child_issues(
     results = _search(jira_client, query, verbose=True)
     if not results:
         print(f"No {issue_type} found via query: {query}")
-        sys.exit(1)
     return results