flux-account-update-db suppresses error from sqlite3.connect

[grondo]

If there is a problem connecting to the db in flux-account-update-db.py, the script prints a generic error:

Unable to open temporary database file: <file.db>

It would be useful to capture the exception thrown by sqlite and print the exception data, so that the real reason for the failure is printed to the user, e.g.

--- /usr/libexec/flux/cmd/flux-account-update-db.py	2022-06-23 09:40:44.000000000 -0700
+++ flux-account-update-db.py	2022-07-13 08:38:31.550533501 -0700
@@ -158,8 +158,8 @@
         new_conn.close()
 
         os.remove(new_db)
-    except sqlite3.OperationalError:
-        print(f"Unable to open temporary database file: %s" % new_db)
+    except sqlite3.OperationalError as exc:
+        print(f"Unable to open temporary database file: {new_db}: {exc}")
         sys.exit(1)