Skip rdrgen tests in CI

tests/test_rdrgen.py

@@ -4,11 +4,16 @@ from io import BytesIO
 from datetime import datetime
 
 import h5py
+import pytest
 
 import edosl0util.rdrgen as m
 from edosl0util.jpssrdr import decode_rdr_blob
 from edosl0util.stream import jpss_packet_stream
 
+if 'CI' in os.environ:
+    pytest.skip('skipping rdrgen tests (CI: h5diff not available)',
+                allow_module_level=True)
+
 
 def generate_rdr_packets(rdr_file):
     """Iterate over all packets in an RDR