tests: Close some open handles

I accidently installed something that is telling me about
unlosed handles in the tests.  Let's clean them up.

<and yes I have no idea wtf I did>

Signed-off-by: Donald Sharp <sharpd@nvidia.com>

tests/topotests/lib/topogen.py

@@ -1114,6 +1114,7 @@ def diagnose_env_linux():
             logger.warning(
                 "BGP topologies are still using exabgp version 3, expect failures"
             )
+        p.close()
 
     # We want to catch all exceptions
     # pylint: disable=W0702
@@ -1122,6 +1123,7 @@ def diagnose_env_linux():
 
     # After we logged the output to file, remove the handler.
     logger.removeHandler(fhandler)
+    fhandler.close()
 
     return ret